Bad Customer Service

Good Day I would like to complain about the bad service we have received from this Company. We ordered a rooter online three months ago and the condition was that we should pay an upfront fee of R816 before we could receive the rooter. We did pay online and when R429 was suppose to be deducted from my account instead an amount of R1162 was taken out of my account. My husband and i have been calling MTN to allocate the R816 payment but that has been unsuccessful we call the Customer Service but non the agents call us back. We have sent proof of payment and a bank statement but nothing has been resolved, instead we got a threatening email that our account will be handed to Legal. We even spoke to one of their team Leader by the name of William he promised that we will get feedback and we have not received any response. We went to the store to cancel the contract and we were told that they don't get involved with online queries we need to call the Customer Service so if no one can assist us what should we do. This has been a bad experience and they have proven that they do not respect their clients and do not have good qualities when it comes to their clients.