Incorrect Contract and Pathetic Service

Created a contract in January with MTN through Mondo. I asked that the contract be app**** to my existing pay as you go number as I did not have another slot for a sim card. This was not done and I received a new sim card and number that never worked. In March they started debiting my account but I have not been able to move to my current number nor has the new sim card actually worked. If I phone MTN to cancel they want to charge me a massive penalty for cancelling early and they say the issue sits with Mondo and needs to be handled by them. How is this situation fair to the customer while you continue to debit my account!