Have you tried talking to Giffgaff about the issue?
I've not used them myself but I've heard they offer a good deal for sim only stuff.
As far as I can see there's nobody available to talk to. It's all online and if you want help it's via their forum.
Prices were definitely good. £12/m for 250 mins + unlimited texts and interwebs. Not much good if it doesn't work though.