Cell c bad service

I have been a loyal customer with Cell c for five years.i have two contracts with cell c.I have never missed any of my payment.I have called the customer care end of February to changed my debit order date to the 25th of every month but the consultant only changed for one contract instead of two.No i am due for an upgrade but cant because my account is in arrears because of the returned debit order for one contract.I have called cell c several times to enquirer about as it not my fault that they couldn't get find into my account.I am totally not happy with cell c as i need a cellphone and i really need to upgrade.It was not my fault that they hired *********** consultant and now i am the one who is affected and no one can help me out with my upgrade.I mean like really is it my fault that i called the customer care to change my debit order and the consultant didn't do as i requested and why should i be affected now.I believe that when we contact cell c customer care we should get a complete assistance that would not affect us in any way.This was a really a bad experience and i dont want anything to do with cell c anymore as this is the second time i get dissatisfaction with the service and nothing its been done.