Cancelled tracker contract ---not cancelled after 24 months

REF *** Wow, I have been trying to cancel my tracker contract for over 2 years after I sold my last vehicle. After talking to many people its still not done. I put a stop payment on my account to prevent payments from going through. For the last 9 months I have been inundated with arrear payment calls, messages almost every second week, every time I tell them the same story, every time its not acted on. What to do ??? It is utterly frustrating and a mess.