I know you don't want to tell us the full story, but this is getting ridiculous.
You are saying that Bronte is correct, although I am fairly sure that she has misunderstood you.
You said "correct".
Let's make this absolutely clear.
The Vulture Fund is saying
"If you refinance with us, we will write off €100k"
Sorry, but this makes no sense.
Presumably the Vulture Fund is saying:
"If you pay us €420k now by refinancing with another lender, we will write off the shortfall"
Or are they actually offering you the "Bronte Deal". Accept €100k of this on your home, and will write off €100k. If so, then grab it.
Brendan