YOU GUYS KEEP ON REVOKING MY AIRTIME!!!

I loaded airtime last week and it dissapeared, I called MTN na held on for over an hour to speak to a consultant when I finally speak to someone (Hloni Tsotetsi) they tell me I have to wait for the system to update. I could not accept that and demanded to speak to the manager (Thembinkosi Khumalo) who took another 20min to come to the phone. He advised me that they are having technical issues and im not the only customer who is having this issue and he gave me 50mb data as the issue was to be resolved by the end of business that day which never happened and no one got back to me(REF NUMBER ***). I called them on Monday the 20th and held on for another 30min and requested to speak to Thembinkosi Khumalo who was suddenly busy on another line for another 15min, the consultant came back to me saying the airtime has been loaded and the manager will call me back till today. on the 21st of April 2015, I was credited my contract airtime as usual and data and did not make any calls from it but I did go on Facebook and job sites on the 22nd, to my surprise this morning I check my airtime balance and I have R30 airtime when I had R100 and 35mb data, I call MTN and held once more for 20