['It was aggravating when I was fired for something I did not do. I knew the company was not for me then', "I'm sorry to hear that.  What made them think it was you?", 'A customer lied about me']
It's unfortunate that they would take their word over yours.  It shows how little they knew you.
When I got fired for something I did not do, it was very aggravating for me. It just made me mad