Praise be to Allah.
The money that is acquired as a result of deceit, lying or forgery is haraam wealth, and it is not permissible to consume it or benefit from it; rather what you must do is return it to its owner and ask for forgiveness from him, so that you will have discharged your duty for sure. (This applies) whether its owner is a Muslim or not, because the sanctity of the wealth of a non-Muslim (dhimmi or mu‘aahid, i.e., non-Muslims living under Muslim rule, or who have a treaty with the Muslims) is the same as the sanctity of a Muslim’s wealth. Our Prophet Muhammad (blessings and peace of Allah be upon him) disavowed those who transgressed against the wealth of non-Muslims and said: “As for the wealth… [that was seized unlawfully from a non-Muslim), I want nothing to do with it.” Narrated by al-Bukhaari (no. 2731). Al-Haafiz ibn Hajar (may Allah have mercy on him) said: From this (hadeeth) we learn that it is not permissible to take the wealth of the kuffaar by treachery when they have been granted security.
End quote from Fath al-Baari, 5/341
Sincere repentance requires you to speak frankly to your company, if that is possible, or at least to stop that haraam income that is coming to you, and do not continue to take it from the company unlawfully. The first condition of sincere repentance is giving up the sin immediately. So long as you still receiving that haraam wealth, we fear that you may come under the ruling on one who persists in his sin.
With regard to what you said about compensating the company by bringing some new customers and not taking the commission to which you are entitled in return, that is appropriate if you are unable to return the money that you had taken unlawfully to the company or tell them what really happened so that they can decide as they see fit.
If you cannot do that, then we hope that what you have mentioned will compensate for what you did of trickery to take what you are not entitled to, and that this will be an expiation for the haraam wealth that you took from them, by means of which you will compensate the company and restore people’s dues, on condition that the money that which you had taken unlawfully will be equaled by the money that you are entitled to for the customers you brought but did not register under your name. If what you took is more than that, then you have to strive to return the additional amount in an acceptable manner, or by bringing more customers for it, until the two amounts are equal and you know that you have restored people’s rights or the equivalent.
The fuqaha’ (may Allah have mercy on them) have outlined numerous ways that make it easier for the one who wants to get rid of haraam wealth to do so. For example, Ibn al-Qayyim (may Allah have mercy on him) said: This is based on an important Islamic principle having to do with the one who has taken something to which he is not entitled according to sharee‘ah, then decides to get rid of it: if the item in question was taken without the consent of its owner and he did not give him something to compensate him, then he must return it to him. If he is not able to return it to him, then he should pay off a debt that the person owes on his behalf. If that is not possible, then he must return it to his heirs. If that is not possible, then he must give it in charity on his behalf. If the rightful owner chooses to take the reward for that charity on the Day of Resurrection, then he may do so, but if he insists on taking from the good deeds of the one who took it unlawfully, he will be able to do so in return for the wealth (that was taken), and the reward for the charity will go to the one who gave it, as was proven from the Sahaabah (may Allah be pleased with them).
If the money was paid with the consent of the giver in return for something haraam, such as one who paid for alcohol or pork, or for adultery or immoral deeds, in that case the money is not to be returned to the one who paid it, because he paid it willingly and took something haraam in return for it. So it is not permissible for him to have both the money and the thing he paid for, because that is helping in sin and transgression, and making it easy for sinners to commit sin.
What else could the adulterer or the one who commits immoral actions want, if he knows that he will get what he wants and have his money back?! Sharee‘ah is far above prescribing such a thing, and it makes no sense. But the one who receives the money should not consume it; rather it is evil and impure, as ruled by the Messenger of Allah (blessings and peace of Allah be upon him). But it is evil and impure because of the way in which it was acquired, not because of wrongdoing to the one from whom it was taken. The way to get rid of it and complete one’s repentance is to give it in charity. If he is in need of it, he may take as much as he needs and give the rest in charity. This is the ruling on all impure earnings that are impure because of the way in which they are acquired, whether that was in return for something that is haraam, whether it was an item or a service. The fact that it is deemed to be impure does not mean that it must be returned to the one who gave it, because the Prophet (blessings and peace of Allah be upon him) ruled that the earnings of a cupper are impure, but it is not obligatory to return them to the one who paid them.
End quote from Zaad al-Ma‘aad, 5/690-691
However, what we advise you to do is follow the path of piety and admit to the company what has really happened, or, at the very least, ask them to stop giving you this haraam commission
You should understand that honesty is the best policy. If we assume that what you fear of being dismissed happens, it may be that Allah will replace it with something better than that for you. Allah, may He be exalted, says (interpretation of the meaning):
“O Prophet! Say to the captives that are in your hands: ‘If Allah knows any good in your hearts, He will give you something better than what has been taken from you, and He will forgive you, and Allah is Oft-Forgiving, Most Merciful.’
But if they intend to betray you (O Muhammad SAW), they have already betrayed Allah before. So He gave (you) power over them. And Allah is All-Knower, All-Wise”
“And whosoever fears Allah and keeps his duty to Him, He will make a way for him to get out (from every difficulty).
3. And He will provide him from (sources) he never could imagine”
And Allah knows best.