I was having trouble with TK website including creating Feedback Forms, picking seats (in J) and generating You&Friends invitations. I was able to generate the invitation from the App. However the remainder of tasks still failed there. Then once my girlfriend got the link, it failed to load or let her create an account. I was going to give up, but thought to try a VPN. I have a free Windscribe account that can log in from Turkey. It turns out all of the tasks including registering the Miles&Smiles account worked perfectly fine there. Hopefully this helps someone. It's still pretty sad that that's a solution and they can't fix their underlying IT, but give a VPN a try if you're struggling.