Double Debit and Poor Customer Service

I am very frustrated with the service I have received from Telkom. On February the 6th I called Telkom to inform them that I have changed my banking details,the lady I was speaking with failed to inform me that the change will only take effect from the 1st of March. As a result I didn’t secure enough funds on my old banking account,and Telkom debited that account only to find that the funds were not enough for that transaction. After realizing this unfortunate incident I then made an EFT payment to Telkom on the 28th of February to try and rectify the situation. My efforts were in vain,as I speak to you Telkom claims that the amount is not reflecting on their side although their agents have confirmed the bank account number to which the amount was paid to be correct on several occasions. Although I have paid the required amount for the month of February,Telkom continued the double debit me. I am not happy with how this whole issue has been handled,I don’t understand how a payment made almost a month ago is still not reflecting. I have been calling Telkom this whole week and they have not been any help to me. I just want them to refund me my money since they decided to double debit me although I have made an EFT payment,I am really sick of Telkom and their poor customer service I can’t wait for my contract to end in May they don’t deserve my hard earned money.