paying for inactive contract

Good day<br> <br> My spouse has a top up 100 contract with MTN that she has for less than a year now and has not been able to make any outgoing phone calls for the past 3 months, we have visited and made calls to the branch countless times where we were told to remove the sim card and re insert it before trying again, we tried a sim swop which did not work, we have not received any feedback and make calls daily to track progress only to be told that we must be in store to troubleshoot where the assistant will remove the sim card and try it in her phone but problem persists even in another device, we have asked how we go about escalating or logging a technical request, and the agent responds by saying they do not know. At this point we are uninterested in continuing the contract with the service provider . thus far we have no contact with any superiors who may be able to get this matter resolved, no reference number for any request/problem logged about the issue and when we request any of the above we are simply told that there is nothing they can do and we should return later in the week.<br> MTN must somehow make up for the inconvenience and cost caused.<br> <br> Regards