MTN is hopeless

I opened a contract for my mom, on my name. This was almost a year ago. To date I am still trying to pay her account online. I have been to the MTN stores countless times, but to date I have not had anybody correctly arrange for me to receive the invoice on my pc. Yesterday a person from MTN phoned me, and telephonically gave me the ref I should use when making payment, yet when I enter this ref, the MTN system does not recognise it? What is wrong with MTN? if you wish to be frustrated beyond measure, then go ahead and enter into a contract with MTN.