Poor Service1-

Its been over a week now without me being able to make telephone calls. I have loaded airtime several times but i every time i try and make a call i get a message that says "You have insufficient airtime". I've contacted the call center several times, I've went to an MTN store in Centurion, where we changed phones and removed the sim card but still the issue is still persisting. I have 3 reference numbers but still experiencing the same issue. I'm currently using the same sim card for data contract. Its only been a few months in MTN and honestly i regret taking up a contract with you guys. Now i'm even being charged R2.60 per minute just because i'm using the same sim card for data contract and i was not told this from start