Is this defamation and descrimination.

Thanks in advance for letting me post and for giving me a legal answer:

We have a state car in our office that was involved in a collision with another vehicle. I send the necessary estimates to the department that takes care of approving repairs. The repairs were authorized to be done by another department that had no authorization to approve the repairs (but I didn’t know that at the time) so it was sent to be repaired. The repairs were done and now there is an invoice to be paid. I requested a check to pay for the repair and the woman in charge of the department that authorizes the repairs, as usual (this happens a lot), acted as if she didn't know anything about such state vehicle or such accident. She said that I was probably trying to repair my own vehicle and charge it to them and she requested my supervisor’s name and number (to report me). The vehicle, after all this state runaround crap, has finally been approved to be repaired and a check has been authorized, but the issue now remains with the woman that insinuated that I was being a thief by having my own vehicle been repaired and charged to them. Is this defamation?

I have been the office custodian for the state vehicle for more than 3 years. I have asked at least 3 supervisors to relieve me of such duty because I don't like dealing with the people that deal with vehicle maintenance and repairs in Sacramento who don't care much about their tone of language plus the work gets complicated due to the many steps that have to be taken just to have an oil change for example. The last time I talked with a supervisor, she stated that they preferred to have a man in charge of vehicles so basically saying that I was stuck with it.