Pathetic service

I have been an MTN customer from the beginning, but in the last couple of months, I have been having the worst experiences ever with MTN. I have no coverage (so has my husband and other people we know), which means that I can't perform my duties as my phone is necessary for my work. I have phoned and phoned and phoned and phoned but nothing gets done. What should my next step be to get a response, the media maybe?