Having been on a virtual tour of GiffGaff's new offices, I think it would be good if all members were given the opportunity to enter into a monthly or quarterly competition to visit GiffGaff HQ and the team. Maybe get some nice goodybags of GiffGaff goodies too.
The winner would be able to go along with up to 3 more guests. GiffGaff would not pay for travel or accommodation, it would be up to the member to consider this before entering. For those who would not be able to visit, but won and enter - maybe these could get a bigger giiffgaff goodie bag - appreciate London is not an easy option for all.
This competition could be a good PR activity for GiffGaff.