All things fair, I feel the need the post an update.

I was finally able to withdraw my bitcoins!

I went through the path of changing e-mail addresses and settings and lots of challenges, but finally step by step I made small progresses.
Not sure whether this was because of changed programming or a change of house rules, but slowly the process started to work as described.
While I am 100% sure my former e-mail address, BTC address etc where correct, by changing all these I was able to retrieve everything.

This makes the title of this thread a bit unfair, though the effort needed to retrieve a fairly small amount of money makes me decide the whole thing is still a bit tricky, if not, it may show some aspects of a little scam.

For me, I like to finish this thread with a kind of "creed of the day" : NEVER GIVE UP !