Terrible service

I picked up by Discovery has been billing me for a vehicle I sold over a year ago. I reported it and asked why they are still billing me for a vehicle I reported I had sold. They said they will look into the matter and contact me back. I am STILL Being billed for a vehicle I sold OVER A YEAR AGO. I would like a credit to my account please and have the Audi A3 taken OFF my Policy. I called now finally getting thru to the right department, going thru various people and departments. I gave him my details; he pulled my profile and then he dropped the call. STILL HAS NOT CALLED ME BACK. This is unacceptable DISVORY Your service has become nonexistent, untrained staff that just don't care to sort out issues.