Unauthorized debit

4 years ago, I experienced bad service from this company, with regards to unauthorized debits. On the 28th November , I sold a car and informed them that I bought another car and I would like to install a tracker @ R99.00. The previous one was R64.00

On the 2nd Dec a tracker was installed and on the 2oth December I was debited R243. 00.without any explanation. I did send them another email and reverse debit until I get explanation. The tracker is R99.00???