Negligence

I have been battling with Telkom for months to make a correction on my account, because they supposed to be debiting my account each month, each month it would decline and they would add rejection fees to my account, I started paying manually. After numerous emails back and forth for them to make a correction and to give the discounts of all the rejections fees, they did not have my correct account number. which I have given to the sales person when I opened the contract, and they debited for a few months, then just stopped. my last email to them, they told me they will credit my account when i send the correct banking details. so i did just that, they sent me an invoice with more rejection fees added and they expect me to pay, when this is due to their negligence. I have sent another email, coz I will not be paying fees that is not my fault.