Are you trying to make your first top-up?
Ways to top up at giffgaff
Online credit/debit card top-up
You can use a credit/debit card to top up online or buy a goodybag. The minimum top-up is £10 and the maximum £30
You can buy a top-up voucher and use it online or by dialing 43430. Where to find a top-up voucher
Recurrence & auto top-up
Set your goodybag to recur each month, so it automatically renews itself. The easiest way to top up is to set up auto top-up. You'll be able to configure the amount you want to top up and maximum amount of top-ups per month.