They will not cancel my account

I called Mtn call centre on the 10 April 2015( ***) to cancel my account but up to date its still not cancelled, i instructed them to take back their airtime and they never did and they billed me April which i accepted considering i used their airtime, same thing is happening this month.<br> All i want is for MTN to take back their money because they are not getting my money this month.<br> <br> I called on the 14th May (***) and Nosipho (if i got the name right) said i would get a call back from MTN by close of business or following day, i am still waiting for that call. This is not acceptable,on the 14th i was holding on the line for more than 25 minutes before speaking to a consultant. <br> <br> YOU ARE WASTING MY TIME, PLEASE SORT THIS OUT<br> <br>