This is not a ransom but your lack of time reading the terms before you use the services. You should check their newsletter regularly if you didn’t support KYC requirements since any exchange services has the tendency to requires. Your funds is already subjected to their terms the moment you send it to them. Their ToS is publicly available for you to review it.
I will believe that they scam you if the KYC requirements is not stated in their terms and conditions before you made your deposit. 1.5XMR is already significant amount.
I get that op should've read the terms of service and whatnot but the thing is, just because they write it doesn't necessarily mean it's legally binding which is why a lot of these services have this clause:
The invalidity or unenforceability of any of these Terms shall not affect the validity or enforceability of any other of these Terms, all of which shall remain in full force and effect.
Up to what extent is applicable to OP's case remains a mystery... One thing for sure is, op wouldn't hire a lawyer for around 200 bucks.