I cannt make a call with Etym

I have had a problem for now over a month when I try to make a call the mtn sytem tells me I have insufficient etym while my account has etym.<br> I have called the 808 call center more than 7 times, and they keep on refreshing my sim card and it works for one call after the problem continuous. I am tired .MTN useless service.<br> Please may a supervisor contact me..this is ridiculous. Pathetic I just want to make use of the service I pay for each month.. if I could I would cancel my contract