Fixed LTE PE

We've recently taken out a Fixed LTE data contract with MTN in Port Elizabeth and it worked very well for 1 week but we are unable to connect to the internet for the past 3 weeks now. We've spoken to many consultants at the call center but with no luck. We were promised a call back from them to assist with the problem but 3 weeks later and we are still waiting for the call back, in the three weeks we called everyday but no one was able to assist us. When calling the MTN store in Cape rd Port Elizabeth we left our contact details and were also promised a call back from the data specialist but we are still waiting 5 days later. when calling the store in Greenacres the person answering the phone confirmed they could hear me clearly but then did not respond to me everytime I asked a question, the operator then hung up the phone and when calling back no one answered the call. we are paying for a service that we are not able to use but we are still been billed for the service for the second month now. Can anyone assist?????? the number in question ***. My contact number is ***.