Thanks for visiting the Giffgaff community
It's good that it has not started yet. That make it easier to refund.
You can contact a personal from Giffgaff by going to here.https://giffgaff.com/support/ask
Just bluff your way through this form and when u get to any more information,explain the problem.
Hope u get it sorted.
Agents talk up to 48 hours to reply but they will always try for 24
Have a nice day!