You can get the settings by dialing Dial *123# . Then select the option to send the settings to your cellphone. You will receive an SMS that has WAP settings in it. Follow the SMS directions then save the WAP settings to your phone.
However, since whatsapp messages are being delivered (albeit slowly), I would have to wager a guess and say there is signal issues in your area. You mentioned it being on wifi too, which is an odd issue. If you don't come right, go into an MTN shop.