DK Watson Car care Collision repair Dave Watson Deceiving, shady and greedy business owner agreed on a bid with me than after work was done threw in extra charges and takes me to collection agency! Salt Lake City, Utah

I had a small dent and some sctratches on my car so I went and got some bids on my vehicle ,I took a bid over to Dk Watson (cause he was close to my house )and he agreed to the bid and to fix my tail light and stuff at a set price we agreed on so I let him repair my vehicle. When I went to pick up my vehicle , I went to pay and he had snuck an extra charge in hoping I wouldnt notice , I DID! He was so sneaky and shady about the whole deal the whole time ! I paid him in FULL ! every dime we agreed upon ! than his secretary called me a month later stating I owed more money , I said "no way send me an invoice" instead of an invoice I got a letter from Checknet collection agency saying I owed $310.00 , No possible way I owe that amount and I have proof! I sent a dispute letter and The proof of the bid we agreed on and my checks I paid him with . Check net does NOT care they want the money so they are going to take that CROOK Dave Watson and do and charge whatever he feels like cause hes their client ! That is complete bull ! so any business any where can fradulanltly send anyone they feel like to a collection agency and get away with this crime?? Where did my consumer rights go ? My good credit is being ruined over the shady greedy doings of this crooked business man , I am sick over this , I regret so bad even going to this business to get work done , I should of went with my first instinct and traveled farther to this other body shop and I wouldnt of had any problems and Im kicking myself hard over that , I need justice and this small time sneaky crook needs to be stopped cause I dont think I am the first person or insurance company he has tried to rip off ,And most people would just pay and let him get away with it cause they dont want to bother or take the time , but I AM taking the time and I will not let him get away with this!! Please help