Missing airtime

I have had such a bad experience with cell c after being with them for so many years and being a loyal customer I loaded airtime and it was taken when I called in for assistance bother the agent and manager we unable to explain what had happened to the airtime they both gave me different stories about subscriptions that i am unaware off and when I asked them to explain this to me the manager became so rude and I did not get any help at all this is so dissapointing as I trusted their service