It was actually a 150 Euro PLUS 25k miles upgrade. I didn't see that the miles were deducted from my account until just now so I was crossing my fingers that the agent missed it.

The fee was to upgrade the fare class in order to use the 25k to get me into BE. I had not slept the evening before so it was all well worth it at the time.

Apparently at AMS (and probably other places) the gate agent is unable to take payment for anything DL related. So, with about 20 minutes before boarding I had to get to the Sky Team lounge to have the change made and then get back. Once there, I was informed they only had one agent capable of taking payments, so I had to wait a bit before that process started. He was having issues getting it to go through but he printed my new boarding pass and said he would take care of it later.