Before I got status, I was offered VDB at CDG when flying to IST. Conditions were I'll be on the next flight and will get 400€ when my ticket had cost me 180€ RT. Needless to say I jumped on the offer as I had only 4 hours to wait and had a week in Turkey ahead of me. I tried to negotiate an upgrade in C on the next flight but the check-in agent winked at me and said: "na don't think so". Anyway I spent the money well and changed my hotel at the last minute from the Sofa hotel to the Park Hyatt for my 3 nights in Istanbul.