bought 1gig data and it was used up within 15min

Bought R150 airtime and converted it to 1gig data which cost R120 then used it for 15 minutes then turned it off and when I tried to search again using google then it said out of bundle. When I called the call centre, the technician advised that they cannot do anything about it as they cannot see what is wrong. When I insisted to speak to a supervisor then I was to hold which I was put on hold for 20 minutes of which the agent came back and promised that the manager will call me back and that was at 14:00 pm and I am still waiting at the time is now 16:27.