What can I do if I believe that I am over chargeed by an insurance company?

Back in Aug 2016 I was in a 3 car accident. I was at fault. I rear ended one truch and he bumped the vehicle in front of him. The car that I physically hit had a dent in bumper and on the hood. The driver of the car in front said that the middle vehicle hit the spare tire attached to the back of his CRV which caused his trunk not to open. I got a police report. I did not have insurance. The front driver filed an insurance claim and it came back as $2,600, the credit collection is saying that I owe and they will suspend my license. But on the break down of the damages, the report said the dent on the trunk door had nothing to do with the accident. The driver basically got the whole back of his car repaired and the accident did not caise him any damage. What should I do?