my mother received the same message from "Revenue Canada" and called to answer to a "mr. adam spencer" (his assistants are "ray" and "anna"). he told my mom to send a money order of 7500 dollars through walmart or a western union (which is very sketchy) or she would be arrested. he told her not to tell anyone, and if the bank asks why you need the money to say its a family emergency. it seems that their new number is 1(343) 885 7631(which is the ottawa area code). they are very convincing and will even give you id numbers, rankings, and an office location. we went to the police and there have even been reports of these people threatening to deport immigrants (who dont know any better) if they dont pay right away. i hope this helps.