Expected to pay for somehting that was never agreed to

We had a Netstar fitted to our Volvo when this was bought in 2004. Account number 173845. Inception date was 6 February 2004. I was the initially owner of the vehicle and the vehicle then was taken over by my dad Mr BS du Randt. I have been paying the subscription for the Netstar ever since – thus 13 years. A couple of months ago my dad experienced problems with the Netstar and a new one was fitted. Nothing was signed. When the vehicle was sold in September my dad tried to cancel the subscription and monthly fee (now standing already R138-99 per month!) only to learn that there is a cancellation fee to pay of R1165-83. This if not acceptable. It’s absurd. What is this based on since he never agreed to anything in writing at all? I am requesting this account to be closed immediately and my further payment that has yet again been processed be refunded with immediate effect. We cannot and will not be held accountable for any funds that has never been agreed to and will escalate this. Regards Christelle van Staden