Bad customer service rendered

I had lost my airtime of R176 on my mtn number which I called MTN customer service several times. To pay my airtime back but Immediately when the agent get to hear my query and be given my ref for my query. About 7 to 8 agents who said they have a system issue I should drop the call and call back. But all of them say the same thing. My MTN number is *** still assistance has been rendered to me.