Xtra airtime a *****

If I could give 0 I would, on numerous occasions I would request mtn Xtra time and not get the exact amount requested. However I have to pay back full amount, reported this numerous times and always get the same response of system issue it will rectify itself. Just requested R60 now and only received R54 I called their call center to log yet another complaint, once again I'm told it's a system issue I should call back later, I asked for reference and the lady couldn't give me one. Mind you when I called the IVR lady did not shy away from telling me that I owe R66 how is that possible when I only got R54. Instead of being transferred to the ***** department by Avela Ntuli my call gets disconnected