A "Top-Up" / "Voucher" will only add credit / airtime (normal top up) to your account and then you will need to pop online to exchange the credit to a Goodybag or a Gigabag or this can be done by phone , you can buy a package direct with a credit or debit card, see below if you need to exchange your balance to a chosen package,or for the next time >>>
How To Exchange Your Credit To A Goodybag/Gigabag
⬜ - Step 1, Go to > My Giffgaff
⬜ - Step 2, Press > Top up
⬜ - Step 3, Press > Select on the goodybags /gigabag icon
⬜ - Step 4, Press > Select on the goodybag / gigabag you want
⬜ - Step 5, On the next page, press > Continue
⬜ - Step 6, Then press > Exchange Airtime Credit OR To pay by debit card put your security code in
>> CLICK PLACE ORDER <<
- Next -
⬜ - Review your basket and click on 'Continue' then click on 'Confirm Order'
Picture Guide if you struggle at all - ➜ http://community.giffgaff.com/t5/Solve-your-questions/Can-I-buy-a-goodybag-gigabag-with-my-existing-credit/ta-p/4101025
Or by phone:
Dial 43430, option 2
If you're topping up by voucher, redeem them via 43430, option 2 to buy a goodybag using the voucher as payment.