I genuinely don't know what's going on at this point. I feel like King does stuff with servers internally because my Piggy bank went away for a good while and then it popped up again after so long. I guess all I can say is that if you really are in the UK, maybe there's a VPN on your phone/tablet you're not aware that…
Ok so you are definitely in a participating country for the contest so like I mentioned earlier, you can try to delete the app and install it again and log back in (You'd be giving up your boosters if you do that) but another thing you can try is maybe get a tablet or phone that you have laying around and log in. Whatever…
I would make the effort of uninstalling the app and log back in but that would of course mean that you'd lose all your current boosters. What country are you from if I may ask?