Airtime disappears

I've contacted the MTN call centre on various occasions with regards to my contract which started in July 2015 but due to the incompetence of the staff at MTN Killarney my contract was not loaded correctly and had to be reloaded again, several times over. A few weeks ago I noticed that my airtime was \disappearing\" and again on Saturday. I have several reference numbers from MTN and from the first issue, nothing is resolved. Yesterday when I called the MTN call centre again, I was told that [URL Removed] is the reason why my airtime is disappearing which nobody knows what that is and nobody can explain but they will all escalate my query. I would like this issue to be fixed once and for all and if MTN cannot get it resolved then I would like them to admit to their fault and incompetence and allow me to cancel this contract and move onto another network."