Cancellation not processed months ago, requests for phone recordings ignored, debt collectors now calling me

I sold my car in January and called in to cancel my contract/service, I was informed that it would be cancelled. I checked this month and saw the debit order was still going off the past 5 months. So number one they didn't cancel the contract. I emailed on the 8th of July and STILL have not received a reply on that ticket(don't bother with email support). I called in last week Tuesday 12th of July and they informed me that it's still active and would I like to cancel, I told them I already cancelled months ago and they need to reimburse me. I requested the call recordings from when I cancelled and I was promised in two days on Thursday the 14th of July I would have a manager call me and go over the recordings. I received nothing until today when I got calls and messages from debt collectors telling me to contact them urgently. That was pointless as the number they give you just rings endlessly. I phoned netstar again and after explaining my entire story again (the person I called last week did nothing, no notes on my profile or whatever so my inquiry just vanished). I demanded a reference number and was promised the call recordings will be sent through to me in the next two days to prove I cancelled months ago. They can track your car but customer tickets just vanish without a trace. Netstar please mark this as urgent and get your debt collectors off my back immediately.