Debt collection: Attempts to collect debt not owed

In late XXXX of XXXX I flew into XXXX for a 3 month job. I rented a car upon arrival since I did not have any other transportation. The next day I returned the first car and was charged {$48.00} dollars for it. I then rented a new car under a company contract that same day. I was charged monthly and returned the car on XX/XX/XXXX. After much back and forth I was at last given the final invoice of that car on XX/XX/XXXX and saw it was {$2000.00}. I felt like I was charged more than this so I added up all the charges on my bank statement and realized I was over charged by {$640.00} which was the exact amount of one charge posted to my account on XX/XX/XXXX. I reached put to the XXXX agent assigned to my company and after explaining the issue and being ignored I went to my bank on XX/XX/XXXX and disputed the charge through them. On XX/XX/XXXX they wrote back to me saying the issue was an errant extra month rental that somehow was created. They settled the dispute and awarded me {$560.00}. I moved on with my life, took another out of state job, and now that I'm back home I see I have multiple bills from XXXX dated XX/XX/XXXX billing me for the {$560.00} I was awarded and now they say it has moved to a collection agency on XX/XX/XXXX and there is nothing they can do about it now. They are claiming that their records indicate their car was returned on XX/XX/XXXX which is quite impossible. The job I was working on was all about covid safety and required the whole crew to sequester in a hotel for three months. I spoke with my bank and they say that when they contacted XXXX about the dispute they never tried to fight the bank on it. I do NOT think this is right and am trying every means to get it fixed.