I fly so often with KLM (20 flights this year so far, four more booked starting next week, four more probable before the end of the year) that I thought I ought to register for Flying Blue.
I had terrible problems because the KLM website said I had already registered - which I knew (i.e., remembered) nothing about. This was finally resolved by emailing KLM direct, they passed it over to Flying Blue, who emailed me in turn. I only managed to get some sense out of their phone system by working out that the 12-digit code at the top of their email should have the leading two zeros ignored, and the remaining 10 digits should be keyed into the telephone keypad when attempting to call them.
I'm all sorted now and enlisted, and have even managed to get 12 previous flights back-credited to my Flying Blue account.
HOWEVER, my husband flies several times a year too. I started the same procedure for him and have run into worse hurdles. I've found his User ID (10-digit number) in my email Junk-Mail box (phew!) but,

his name has been entered the wrong way around on their system.
His name (not his real name, I'm making the name up here) is James Purple. On their system, it's down as Purple James. That does not match his passport. I can see from my own Flying Blue profile that it's not possible to edit one's own name.
Today, I tried to re-register him, using a completely different email address. But at the end, it just said "you already have an account" and shut me out. How did they identify him then? I reversed the names presented - now correct - and offered a different email address. I had also cleared all the cookies off my browser first, and cleared the history and cache.
How do I get him out of this electronic muddle and registered? Any ideas?
Many thanks