My monthly data disappeared

2 months ago I bought data bundles for R160.00 and they lasted for 2 weeks only.I called MTN and I spoke to Clinton (Team leader) who took a call from a call centre Agent who was rude,and he looged my enquiry and said I would be called back.I never received a call from MTN.I called MTN again and I spoke to somebody else who said the manager or Team leader will call me back, to this day none has called me from MTN.I again bought R160 monthly bundles on the 1st September and today my bundles are finish according to the sms I received,while I received an sms 2 days ago which said my night express 50 percent was finish. I do not understand how possible this is as I am using WiFi at work during the day in weekdays. Can someone from MTN please call me and tell me what the hell happened to my bundles.I have heard lot of stories about people' s bundles being taken or disappear for no reason and I never thought I will be the next victim and it seems to be happening a lot now or should I say every second month. there is absolutely no service received from MTN at all!!!!!