How's about a yearly giffgaff bonus of say 10pounds. And a couple of rankings leaps For fun? I think loyalty is something that is no longer valued by a lot of companies and it should be. I see a lot of giffgaffers coming and going also so maybe this little incentive to stay may just sway a few people from leaving.?
I have seen this suggestion a couple of times before and yes, I agree.
What I would say is that it shouldn't be a monetary thing, rewards can be just as meaningful in other ways.
There are many milestones people can reach on giffgaff, for instance length of time/loyalty OR a couple of days ago I realised 100 best answers. You could have a visible achievements section on your profile with badge awards for say getting your first best answer or perhaps going up in say 10's or 50's, that sort of thing.
Something fun could work just as well or other incentives in recognition.
Maybe suggest this in the ideas/labs section 🙂