carib's mistake was saying that the play would be cancelled "(send ss number)...or else". Who ever wrote the message, did so without realizing that they gave the guy an option to cancel a wager that had already started. A bluff that backfired.
Now, if this guy is known for charge backs then. It is possible that they were asking for the ss no. to verify that the card wasn't stolen. Wanting the confirm this as quickly as possible, they added the key "or else your play will be cancelled." thinking that this would get the guy's cooperation.
I can't say for sure what the right decision is, because some of the information can't be confirmed. Though, it seems that Carib should live up their staff's mistake, even if it is a scam.