unauthorized accessed my bank account,

i have a mobile contract with Telkom and my monthly subscription is R369. One of the contract obligations is, debit order to go through on the last day of every month. A paid via EFT was made in April and May 2015 but Telkom debited R737 into my account on the 15th May 2015 where-else an EFT has been paid days before they inconveniently debited R737 into my account on the 15th May 2015, unauthorized and not engaging with me regarding their misconduct. logged a case with the above incident occurred on the 15th May and was promised a payment will be paid back into the bank account on the 22nd May but unfortunately, no payment was made and was again promised when following up on the 22nd the payment into my account on the 29th May. I was assured that it will definitely appear into my account as promised but with no luck. Made a follow up today with Mbali, the manager but with no positive conclusion.