Bad service with Cartrack

Good Day

I would like to log a formal complaint with Cartrack, I had an agreement with them 5 months ago to debit R99 for a tracking device that was on special but to my surprise they've been debiting R199.00. I have tried to arrange with the numerous times but I'm failing as they keep debiting this R199, all I want now is Cartrack t fix this mess or cancel my contract with them.

Thanks