Grievance for debt collection by Wesbank on an account for a vehicle that was settled by the insurance

I recently had a car accident with a vehicle that was financed by Wesbank (VW Financial Services). Subsequent to the accident the outstanding amount on the account was settled by my insurance. A few months down the line while I assumed the matter was settled I received a letter from Wesbank informing me that the there is an outstanding amount on the account. My attempts to get clarity on the matter have gone in vain. I recently started receiving calls from MBD debt collectors informing me that my account has been handed over for debt collection. I am currently distraught and don't know how to address the matter. Please help.