This has happened to me many times in the past couple of weeks. It is always on the final green when I am about to win (often by two or three strokes). In the past week, it cost me 23.4 million coins (5X in the Bellagio room and once in the 900K room...Manhattan room, I believe?).
I call them out sometimes by posting on their profile page about them cheating. I also started posting their usernames in our CC forum for those who care to block these players. A couple of times, I have also written to the owner of the cheaters' country clubs. What is amazing to me is that they have allowed the player to remain in their club! In one such case, the guy gets the same complaints all the time of cheating in this same way with posts on his profile page every other day and complaints to many members who are in the club with this guy. Nothing.
I have also written to WGT about this twice in the past two weeks (naming names) and they don't do anything about it.
Players like this have made the coin rooms a lot less fun. It boggles my mind that someone would have such low integrity and character to cheat like this, but unfortunately it exists here. It also boggles my mind that any owner of any country club on here would allow players like these to give their entire country club a black eye, which is the case.