This topic prompted me to check out the website of Siranie; an establishment that closed down quite some months ago, yet their
website remains online. Locating their address on Google maps reveals a new establishment at the same location called "Montra Wellness Amsterdam", with a link to
their website. The prices page ("Tarieven") lists prices for Thai massage very similar to those of Siranie.
I certainly can't promise that you'll find a happy ending here, but it looks possible that Siranie might be back and operating under a new name and website. If that is indeed the case, it could be a great option. The last couple of times I visited Siranie before it closed, they seemed to be very cautious about revealing the extra happy ending option (which cost extra).
Then again, it might just be coincidence, and have nothing to do with Siranie.
I might need to check this place out myself next time I'm in Amsterdam. Probable worst case scenario is that I just end up getting an hour of Thai massage for €50.