Can't cancel a simple contract and continously bugged by rude call agents

This is my second message and still this issue hasn't been resolved. 5 months ago I told matrix to cancel the contract because the vehicle was written off. The gentleman that called me to upgrade my unit advised he canceled it. A month later some rude B#$ch called screaming at me on the phone to pay my account of which I told her my account was canceled she put the phone down on me while I was still speaking to her. 2 days ago I get a letter of demand and a negative credit listing *** . I'm very upset because on my 1st review I was advised the account was canceled. If this is not sorted before Friday and the listing removed I will contact a lawyer and take immediate further action because I had enough of this. The vehicle was written off you can check on your system it hasn't been mobile in forever so why must I pay when I told 6 call agents to cancel a contract . The lady that was rude to me I'm still waiting an apology for you. I have never this issue with Netstar therefore I moved all my new vehicles to Netstar. I get better customer service in less than 24 hours of my query. Well done Mix telematics on loosing a loyal client for many years