Thrifty car rental is a ****

My friend told me that Thrifty car rental is a ****. She said they find anything, visible or not, and make you pay for it. I was desperate because it was Sunday and Avis was closed, so I chanced Thrifty. And just as my friend said, when I took the car back yesterday after a smooth trip, they found a growth on the surface of one tyre and found a barely visible indentation at the bottom of the passenger door. Both things not visible at all, otherwise I would have seen them during the inspection when I fetched the car. It's like they knew those things were there, because the inspection guy went straight to the passenger side and 'found' those things when I brought it back. I was so angry because I had already been told they will pull every trick to make sure they keep my deposit. So I told them 'I knew you were gonna keep my deposit no matter what happens, so keep it, you are ******** and you will be out of business soon'. So guys, please wait for Avis and get a rental car from them if you want peace of mind and if you want your deposit back.