Holding on to my deposit

I would 0 stars if this was an option. Rented a car from them which already had scratches on them. Upon returning the car the gentleman checking the vehicle stated that there was a scratch on the left front bumper. I signed the claims form although I didn’t agree with him. Now upon checking the vehicle check sheet I was given I can see that the car already had a left front bumper scratch which is exactly what has been written on the claims form. I have emailed and emailed and no one can give me a response as to what they are charging me for and they are holding onto my deposit. This is wrong and there customer service is terrible, I can clearly see how there money is made, through wrongfully charging customers for damage that they don’t repair. They are also gave me a GPS that doesn’t work and I was told I would be refunded by the guy at the desk and still absolutely nothing has been returned and no communication has been given whether they will be giving my money back. I don’t see how a company can think it’s ok to hold on to someone’s money wrongfully. I come to SA every year with a group of friends and I won’t be recommending Tempest to any of them.