Definitely don't miss their phone call. They called me on the 22nd of February, I have called and left voicemails every day since. I've gotten 4 calls back all from the wrong department, all stating that someone would call me back from the right department in a day or two, and its never happened.

No one ever answers the phone.

Edit:

Finally got a hold of someone there and got two nights booked in Amsterdam. Only problem is we're leaving before the certificates come. Guy on the phone said the certificates were good for 1 year. I wonder if that means I can cancel my booking and use them at another Hyatt of my choosing? Anybody know?