So, I was lucky after all. Waited about 9hrs for the problem to solve itself, of course I also submitted the ticket to Support, but it was Saturday, and I got the reply that "Support is available between the hours of 9:00 to 19:00 Monday to Friday". Today around noon, I took care of my island (mines, buffs etc.) and then tried accessing my Return to BN ... and it worked. I completed the adv. and now all my generals and troops that survived are back. I lost 1 tome, 1 glue and some granite due to expired premium, but I guess it could have been much worse.
I'll post the details soon.