Taking this thread a little off topic....
Why in the world would your friend pay up front a contractor
- that he /she had no address for
- possibly had no references for
- maybe never saw previous examples of his work
It looks like your friend handed $$ to some one they really didn't know very well, and then trusted them to do a good job. Ever heard of part payment up front (a good faith retainer) and the balance upon successful completion of the job? Reputable contractors do not require all their money upfront. Do you pay your mechanic before he fixes your car?
Reporting the guy to CRA seems like a good idea, and CRA can really do a number on a tax cheat IF they get their hooks into them [that part I have seen in action, close-up, I usually get a call to get involved after it's too late for the tax cheat though]. But...
The reality is that CRA will want you to build a pretty good case for then before they take the ball and start running with it (they gets lots of spiteful ex-husbands and ex-wives trying to stir up things, when there's really no case there). If you can't provide more info than a name and cell phone number, there will likely be zero follow up. In other words, if you can't find the guy, they aren't going to find him for you.
The lesson(s)? here are that proper planning is required if you're undertaking either a home reno project or helping CRA chase tax cheats.