Withdrawals from Bank account

I entered into a LTE agreement with Telkom through one of their Agents and signed a Debit order for R 249.00 / month. Telkom then tried to withdraw more that this agreed amount every month. I have had to reverse their withdrawal at my bank and pay the correct amount by EFT. I logged a complaint and received a reference Number. I have called their call center at least 10 times ( for up to 60 min/time). I have e-mailed to various employees copies of signed agreement and copy of invoice. No One has in 2 1/2 months come back to me from Telkom to try and assist to sort the problem out. They just keep on withdrawing from my account. I am very ... Very disappointed with their call center and lack of response to resolve the issue. I WOULD CAUTION EVERYBODY TO NEVER SIGN A DEBIT ORDER WITH TELKOM!