Emergency lines not answered !!!!

I have cancelled the Tracker unit on my old car in May 2015 (Car Sold) with the agreement paying the outstanding amount. It's still not cancelled after many calls and promises that Tracker will get back to me and not bill me anymore. I have recorded the phone calls dates and times and contact persons. On 21 July at 14:02 I received a message \Tracker attempted to contact you wrt your cancellation query. Kindly contact the retentions department on ***. WE WILL CONTINUE TO BILL YOU FOR SERVICES". I immediately called back at that number and *** and *** and the emergency number for reporting a ****** vehicle *** for a whole hour I could not reach anyone"