Overcharging and disregard of client complaints / queries

Had tracker installed in one of my trucks . At a later stage this year decided to fit both with dashcams. Because the dashcams had ability to track & protect, I asked agent to cancel original tracker and thereafter only fit the dashcam on that truck. He confirmed cancelation and proceeded with install. After checking statements, it was noted that I was still being charged for the tracker. Queried the overcharge. It's been more than three months and still no corrective action has been taken! All communication with agent saved and sent to Cartrack, yet they are ignoring the issue hoping it would go away. Completely taking advantage of the fact that they are able to just debit your accounts as they please.