There's something about recruitment agencies. For both candidates and hiring companies, seems they are quite money minded.

No empathy. But I guess they are sales organizations at the end of the day, candidates' and companies' satisfaction is very low on the list. All agencies claim to be the best anyway.

But it's a good thing you're trying to get everything written, talking to them when they're demanding money is the same as talking to debt collectors. Maybe less than stellar advice, I'd just hold my ground, don't pay out of fear. It's preferable to get into official litigation vs. feeling so shitty abt ppl hounding you. At least you'll know the lawful outcome and then work things out.