CNAC CF Capital Bob Unlawful interest Mesa Arizona

First I found out they charged me for repairs that were nver done. Second they sold me a vehical that was not in safe driving condition such as the engine light was on and air bag at purchase. Third when I pulled my credit report it stated i owed 3700 and when I called them to ask whats up with this garnishment deal they responded that i argeed to pay 4589 dollars well i never agreed to that and thats not what my credit report says as far as balance. I was never served by a process server and maybe im wrong but when you sue someone its for a certain amount and should not acumalate interest. I also know for a fact that they secretly changed the sticker price cause with what i made in payments on the car it should have been paid aff in the 3rd year i had it cause i made double payments every other month with my bonuses from my employer.