NO service let alone poor service

I have now had no ability to make calls from my phone for nearly one due to MTN for some unknown reason. Have been into the local branch and contacted various people via email to no avail this despite my contract being paid monthly via debit order and even an extra amount of top-up added last month to try and get additional airtime. If this cannot be resolved how on earth will I ever get a refund. No feedback and wasted hours on this. Plus I am in my 70's and it is dangerous to be without comms. It appears someone on MTN changed my contract how???