CELL C and wrong debits !!

I have been with Cell C for a number of years now. But now I HAD IT, Cell C went and debit the wrong amount of money from my account. Now the revised the money back, but still never went and debit the correct amount. Now my account is in arrears they want block my line. When to the store they said it my fault and Cell C wants a double payment end of this month before they can activity my line. IF THIS IS HOW YOU GUYS DO BUSINESS SORRY THEN I'M DONE.