Help: How to easily buy data & minutes online for my four kids with one account

Hi,

I am trying to set up a system where I buy data and minutes online for my four kids.

I would just like to log in, specify a cell number, select so much data and so many minutes and repeat four times and then pay by credit card. I've tried to register on MyVodacom but they want a different account for each cell number and you have to have the phone with you to get their SMSs etc.

Surely there tons of are other people with a similar requirement. Can anyone help point me in the right direction?

Thanks