Shocking Service from Netstar

I had a tracking contract with Altech Netstar on my son's CITI Golf. I sold that car, and on the 28th of August emailed Altech Netstar to cancel the contract. On the 30th of August, I received a reply saying that the "Retentions Department" would contact me to assist me. They never did. Instead, they continued to bill me for a vehicle that was long out of my possession. When I disputed the payment, they handed me over to a debt collecting company (which could affect my credit rating). After speaking to the debt collecting company and explaining that the fault was entirely Altech Netstar's, I phoned Altech Netstar to find out what was going on. The consultant I spoke to admitted that the fault was entirely theirs, and that my case would be referred to the senior members of her department, one of whom would contact me 'in the next day or two' about cancellation of the contract (finally), reimbur*****t of my payments, and an instruction to the debt collecting company to clear my credit record (I have the case number of the call). Ten days later, I have still heard nothing. This is shocking service for a company supposedly committed to client service.