Praise be to Allah.
It seems that it is difficult for you to take off your hijab because of the presence of non-mahram men in your workplace. If that is the case, then you should note that mixing of women with non-mahram men leads to many negative consequences, such as being alone with or looking at a member of the opposite sex, speaking softly, temptation, and other things that are no secret to people of insight. Please see question no. 1200 for evidence that free mixing is haraam.
If a woman is faced with this problem and the time for prayer comes whilst she is at work, and she cannot delay it until she goes back home, then she should pray in the most concealed place in her workplace, covering her hands, face and all of her body in front of non-mahram men. We have already stated this in the answer to question no. 39178 .
Your saying that it is difficult to take off your hijab in order to wipe your hair and ears when doing wudoo’ makes us wonder: how do you wash your arms and feet in the presence of men?
You must be aware that the arms and feet are part of the ‘awrah which must be concealed from non-mahram men. As for the face and hands, there is some difference of scholarly opinion, but the most correct view is that they must also be covered. See question no. 11774.
It is permissible for a woman to wipe over her khimar (head cover) in the case of necessity, such as when it is very cold, or it is difficult to take off her hijab and put it back on.
Shaykh Ibn ‘Uthaymeen (may Allaah have mercy on him) was asked: It is permissible for a woman to wipe over her khimaar?
The well known view in the madhhab of Imam Ahmad is that she may wipe over her khimaar if it goes under her chin, because it was narrated that some of the womenfolk of the Sahaabah (may Allaah be pleased with them) did that.
Whatever the case, if there is some difficulty, either because the weather is cold or because it is difficult to take it off and put it on again, then there is nothing wrong with wiping in such cases, otherwise it is better not to do that. End quote.
Fataawa al-Tahaarah, p. 171
It says in Sharh Muntaha al-Iraadaat (1/60): It is also valid for a woman to wipe over a khimaar that goes under the chin, because Umm Salamah used to wipe over her khimaar, as was mentioned by Ibn al-Mundhir. End quote.
So long as the khimaar covers the ears, it is sufficient to wipe over the khimaar and there is no need to put the hands under the khimaar to wipe them. Similarly, if a man is wearing a turban, he does not have to wipe his ear too, even if they are not covered; rather that is mustahabb only.
Shaykh Ibn ‘Uthaymeen (may Allaah have mercy on him) said: It is also Sunnah to wipe whatever part of the head is uncovered, such as the forelock, the sides of the head and the ears.
Fataawa al-Tahaarah, p. 170
A Muslim woman must strive to fear Allaah and obey His commands, and avoid that which He has forbidden, and keep away from working in mixed environments, which may earn her the wrath of Allaah. She should beware of giving this world precedence over the Hereafter, for it is transient pleasures, but what is with Allaah will never fade away. It is narrated in a saheeh report that our Prophet (peace and blessings of Allaah be upon him) said: “Whoever gives up a thing for the sake of Allaah, Allaah will compensate him with something better than it.” Classed as saheeh by al-Albaani in Hijaab al-Mar’ah al-Muslimah, p. 49.
We ask Allaah to help you to do that that which is best for you in this world and in the Hereafter.
And Allaah knows best.