Cell C making money out of people.

I am very upset with cellc I've been a loyal customer since I don't know when. But seems like in the last few months they just trying to make money out of me. I have set a debit order to go off every month of which it does. This is the second month they taking more money of which they should, why I don't know and when they have to pay it back it's a long **** story.