MTN, no help for 81 year old widow.

On behalf of my mother JM Booysen. I have been a client of MTN for over 20 years and have always just used my monthly contract allowance. My extra spend limit is set at zero. In April my bill was approximately R3000 more and May it was approximately R4000 more. I have visited 4 stores, phoned 7 times and emailed 15 times over the past month to resolve it. I have requested an itemised bill and MTN have not been able to provide it. During our last correspondance MTN promised to escalate the query and supply an answer within 3 days, that was 7 days ago. Now i receive an SMS to urge me to pay the outstanding amount else my line will be affected. As an 81 year old widow this is getting extremely unpleasant.