If you have been charged twice for a goodybag the second one will be queued and will go live as soon as the current one expires.
To cancel your queued goodybag between the moment of your purchase and 24 hours before the expiry of the active goodybag, simply follow this https://giffgaff.com/profile/payment-details link to your payment details page .
And under next goodybag, you will find a button to cancel your next goodybag(see image). Clicking on this button will allow you to cancel your queued goodybag.
Your payment will be refunded back to original method you used to queue the goodybag e.g credit/debit card.
If you have any issues cancelling the queued goodybag please contact a giffgaff agent.