car loan

This company has been overcharging me for the vehicle that I purchased through them. The loan was for $7299.70 with a percentage rate of 22%. It was my understanding that the finance charge should have been $1605 but they charged me $3230.96. I only owe $1500 and they are asking me to pay $2999. They claim the excess is an interest charge which was not stated in the contract. The contract talks about a finance charge that is subject to change on a daily basis. It stated nothing about interest. I have tried to talk to them about it, all they have done was get nasty, hang up ,and threaten to reposess my vechicle.I told them until they can correct my contract i was not going to pay anything. I just wanted to pay what i owe. I think that this company need to be investigated because I have paid over $8000 dollars and and they are still trying to get my vehicle.