So if there is no surcharge on the part of the hotel and you were connected to AT&T, where you entered your AT&T account number and PIN, and the phone charges end up on your AT&T bill, how is this a Sheraton HK phone scam?

Is AT&T telling you that you were not connected to them, but rather to someone else? If that's the case, how did your AT&T account number and PIN even work?