Sold car but struggling to cancel tracker

I have 2 vehicles with Cartrack but I have decided to sell my one car because plan one so I need to cancel the tracker because I cannot pay for something that I will not be using since I’m no longer the owner of the vehicle. I contacted car track to inform them that I have sold the car therefore I will need to cancel the tracker for the sold vehicle. I was told that the new owner will need to take over the car tracker (which is fine but that’s needs to be his decision) or I need to pay a cancellation fee of R2600 now that is what confuses me the most. Why do I need to pay R2600 to cancel when I have never defaulted or claimed. Someone please help me understand how this works or if this is even right.