Have you restarted the phone yet?
Are you in the uk?
Do you have credit or a goodybag?
call 43430 and choose option 2 (buy a goodybag) and listen to your up to date balances. (you dont have to buy a goodybag choosing option 2)
What does it say ?
Sorry to hear that. Since it's been more than 24 hours Click, here for assistance https://support2.giffgaff.com/app/ask/Number-transfers/Transferring-my-number-to-giffgaff/form/Agent... often reply within 4 hours most cases but can take up to 24 hours in busy periods. They do work 7 days a week from 8am to 11pm.
Find agents reply here "Messages: From Agents" which is half way down the right hand side of your "My Giffgaff" page
Or via this link https://giffgaff.com/support/questions