Product differs from what is requested

Whilst doing an upgrade of an existing MTN contract, I took out an additional and supposedly identical contract on my account for my wife. The contract specifications where as follows: My MTNChoice 100 as a closed contract, i.e. when the inclusive minutes, data or SMS's are depleted recharging is required. The upgraded number did and still does comply to the specifications. The new contract on the other hand was not set up as such and has been the cause of excessive bills and payments on my behalf. After eventually speaking to a call centre agent I was informed that the new contract had been incorrectly loaded and the error was 'rectified' and someone from the billing department would contact me within 24 hours. 3 weeks ago. Upon receipt of an SMS indicating that I am currently being charged from my MyMTN Choice price plan I contacted the call centre again to ascertain why I have received this message, to find out it was never rectified. The call centre agent assisted me in rectifying the problem, kind of, and indicated how I can verify this myself. When asked who is liable for the cause of the problem I was told that the sales consultant should be. And I have to pay the bill?!?