Need my credit and compesation for all this trouble

I have an account with mtn which has two lines all was well until I requested a credit increase and it was granted .I did an order on the same day so I could get an anniversary present for my wife. The shop got system issues and I had to cancel the order after that all my available credit was taken away and currently at 0 from 2100. I have been calling the call center for weeks and my issue still not resolved while I'm still paying. Need help please