Waiting 48 hours to sign up to the app?

[Ready22]

I've just bought an O2 sim from the shop but for some reason it's not letting me log in until 48 hours. Although, somehow it works fine to log in on the website.

[pgn]

Have you topped it up, @Ready22? You may have received a voucher in the shop containing whatever price you paid for the Sim card as a credit to be applied to it by dialling 4444 to top it up.

Other ways to top-up after first top-up are here, Guide How to Top Up (PAYG)  assuming you got a Big Bundle SIM

If you purchased a Pay As You Go: Introducing "Rolling Plans" PAYG SIM, then you will have needed to register a card to get the SIM working, and this may take 24-48hrs for payment to process through O2's systems before your card and number become active.

Your MyO2 App, if you have installed it, will help prove this - otherwaise contact O2 on Monday, all the ways here: Guide: How to find help & contact O2 

Good luck, @Ready22 - welcome to O2!

[MI5]

@Ready22 

Have you tried deleting and reinstalling the app?