Bad service

I had a contract(tracker) with this company ,then before contract expires the car was sold ,I called them to jnfkrm the about canceling they told me they can love the tracking system tk the new car that didn't happen and they kept on trying to debit money on my account. I have been engaging with them as of 2019 they haven't even installed the device and kept on calling me each time a new agent calls n say OK I will help you to tlcheck a lace where they can install it until the contract expired. Now they've put my name under non compliant creditor which affects my credit score yet I have a letter they sent for contract expiry and tracker still not fitted until now so their service worst I have seen