Terrible Service at MTN Stoneridge and MTN Customer Service

I am absolutely disgusted at the attitude and service of MTN. In February I entered into a special promo offer Sh@reLink MW40 for 10GB daytime and 10GB late night data but have only been issued with 5GB which ran out some 8 days ago. Despite daily visits to Stoneridge outlet, numerous escalations and 4 e-mails to a certain Warrel Maritz absolutely nothing has to date been done to resolve this problem. This has caused us untold aggravation and frustration as our internet has been desperately needed with an overseas guest. MTN appears to have no concern whatsoever for their customers. To date we have not even had the decency of a reply! The store tell us they are unable to assist other than to "escalate" the problem - their superiors at MTN are unreachable by all accounts.