Unresolved matter

Received a letter of demand Ref: EFF 017204 from Norman Bisset & Associates for an outstanding amount relating to a contract that Netsar had failed to cancel on my request . I had changed vehicles and requested Netstar to fit a new unit to the vehicle I was taking delivery of and cancel the contract on my old vehicle as I had sold it and the unit was fully paid up, however, even though my debit order for the new unit was going off monthly, I was still getting SMS's from Netstar stating that I had an outstanding balance, which was accumulating monthly. After numerous calls and emails for almost 4 years trying to resolve the matter, it was finally resolved, or so I thought, last year with assistance from a gentleman in the Netstar legal department who after investigating my query, informed me that the issue regarding the cancellation of my contract was in fact with Netstar and that the matter was closed. I have had no more correspondence for over a year since sorting out the matter until now. Clearly the Netstar department handling contracts and accounts still have not closed out this issue, bearing in mind that I had been trying to resolve this issue with Netstar for over 4 years prior to this. This level of service from Netstar is unacceptable.