Unauthorized debit order

I just received bank notification CARTRACK CTR*** -237.50 from my bank account. Why will you do that? Our arrangement was that you will debit R200 for 3 months for that call out fee, why did you change the terms of our arrangement without engaging me. If you don’t want my business anymore, just say so and I will move to other tracking companies. You know you debit on the 25th, and you did debit on the 25th of July. Why did you debit my account again on the 07th of August for the sum of R237.50 without my permission.