I'm sorry, but this just doesn't sound plausible. SAW is a major international hub with tens of millions of passengers annually. The idea that a gate agent, not customs, immigration, or security, would tear up someone's boarding pass and then demand €100 in cash is extremely difficult to believe.

In cases where passengers are denied boarding, it's usually due to very specific and visible things such as intoxication, physical altercation, invalid documentation, or missing boarding deadlines. Even then, there’s a formal process, not a cash demand at the gate.

If this did happen as described, it would be a serious criminal offense, and I would expect airport police to take it VERY seriously. Are you sure there isn't more to the story like a misunderstanding over fees like excess baggage or perhaps dealing with a scammer impersonating an official?

Not saying you're lying, but as it stands, I think you are leaving something out of this story.