Cant load data with *147#

For the last three weeks I have been trying to convert my airtime into data. Always connection problem or invalid MMI code. I have phoned in twice to the customer call centre where I was informed that they are not aware of any problems on *147# self help number. I was also informed that my phone needed an upgrade and that is why I am getting this error. Colleagues, friends and family are also on Cell C and complaining of the same problem!!!! How can there not be a problem????? And why is it taking so long to sort it out???? Either there are a lack of communication at Cell C or their operators needs more training.