Oline top-up?!

I have recently tried to top up my mobile phone online. It took my card details, name, billing address etc. but i have yet to receive it....? its now been 4 days. I thought the whole point of online top up was to make it more convenient! I ended up having to go to the shops to buy credit anyways... Well i guess we learn something new everyday - just get up off your ass and go to the shop!