Praise be to Allah.
There is nothing wrong with dealing with companies on a personal basis, with nothing to do with work, even if one is given discounts and treated with special care because of that personal relationship.
Accepting gifts from clients is not permissible, rather it is haraam, as stated in the hadeeth. Gifts offered to an official because of his work belong to the work and not to him; it is not permissible for him to keep anything for himself and he must leave them for his work, because if he were to sit in his house he would not have received any of those gifts. The evidence for this is the saheeh hadeeth narrated about a man who was given gifts when he was working to collect the zakaah, and the Prophet (peace and blessings of Allaah be upon him) denounced him for that.