Cell C be warned

I took a cotract with cell c.. with a fixed amount for data and a router. With a debit order being loaded. However this fixed amount got almost doubled!! After upon they blame me for not putting a limit.. ridiculous!! None the less next month again wrong amount even after i added a limit... so i stopped the debit order with my bank.. and paid with EFT but even im paying Cell C debits my account..and wrong amounts too!!! I went to the cell c branches 4 times!! I called 17 times... and still they take money thats not owed to them!! And even block my services!! But im reporting them to the onbuds man... and they never call you as promised also