Awkward social situation

So I have a group of not very close friends from a climbing group. It is a fairly big group that you don’t necessarily know everyone in it. We were all planning to go on holiday together. The trouble is the hotel arrangments is we need double rooms. A friend of mine whom I’m not close with suggested and confirmed a number of times we’d share a room together. I generally don’t mind sharing rooms in a dorm like situation. I’m a bit more reluctant to share a double room with a stranger. So yesterday I transferred him money for the trip but he then messaged me saying my new roommate is X. I felt he really screwed me over and not sure why he didn’t at least say something before I paid, as now I would have to share a double room with someone I don’t know. Am I the only one who thinks i shouldn’t let him off the hook so easily?