No discount of sms/refund of overcharged bill

I called MTN on 13 April '15, I noticed that my sms's were not discounted and they should of been as I have a contract which includes free sms's thus my new bill: R355.00 incl VAT this would come off May, they said they would fix it but they could not guarantee that it would be fixed before debit order date. I called again on 30 April my May bill was now R335.49 incl VAT my sms's were still not discounted and of course they had no record of the R355.00 as they switched to the new online statements. I was charged the R335.49 in May. It was said in June there would be a mass refund as the same thing has happened to many people. I checked my statement to be billed in June, there was no refund included in my billing amount. I called them on the same day I received the statement 11 May '15 to discuss, the woman said they going to do the refund, my bill for June should be R320.50 - R14.99 (over charge in May) = R305.51. When is this going to happen? It is annoying to call 808 because most of the time I get cut off 2-3 times before I get through to the call centre and the wait is 20 min max each time. Please fix this, its getting ridiculous.