Hide behind a verbal conversation

Couple of years ago I did a telephone call to Them to sign up for a tracker as my insurance demanded it. This year January I decide to trade in my car and buy a new once. I sent them an email, completed that online form and phoned them. The goal was to transfer the unit into my new car but absolutely no response from them. I then drove to their offices to hear that they charge more than R800 to transfer the unit. (this should be a free service). So, I decided to cancel the agreement. Just to see this month they took nearly R800 of my bank account. Apparently, I still had 6 months left on that verbal agreement that I have forgotten about years ago (at my age). Regards Leon van Rensburg ***