@dox73 Please start by rebooting your phone to allow the goodybag to kick in. Failing that check if there are network maintenance or coverage issues by going here: https://giffgaff.com/coverage-and-service.
If those fail the next step is to check your payment history and My giffgaff pages to see if the goodybag has actual been credited to your account.
What does it show? if no goodybag transaction is listed and your balance is 0 you will need to address this with a giffgaff agent to investigate.