Stranded abroad with no help from MTN

I have been stuck overseas with a non working phone for several months now! Roaming was activated with MTN before leaving and it worked for a while and then just stopped. I've been emailing and sending messages over Twitter to MTN for months now, most of the time they just don't reply and when they do, all they say is that they will get back to me once they have some feedback. MTN have left me stranded, with no feedback, no resolution, no progress for several months including over Christmas and New Year, unable to communicate with family and friends and unable to use my phone whilst overseas when I need it most.