I would absolutely contact Microsoft about this. They should be able to help you get things sorted out. If you're calling Microsoft in Canada, I would personally recommend selecting the French options (even if you don't speak it), as you are almost guaranteed to get someone Canadian who can also speak English as opposed to someone in a foreign country who has a really strong accent that you can't understand. All you need to say is you accidentally selected French (oops).
Personally, I would likely delete the profile from his Xbox, and then make my own account and set the parental controls of the console to where you want them, and then suck up the $60 mistake and go with a family pack.
One suggestion once this gets sorted:
Get a Live Gold Family pack, and set up a gamertag for you (even if you don't play), then add your son's gamertag to your family pack, and then you get to set the permissions and such for his profile (including whether he can play certain games online, and what the highest rating of a game he plays can be). You'll also be able to monitor what games he plays, even if he is playing away from home. It will give you more control over the content he is exposed to, and will give you better peace of mind while he is playing his games.
The Live Family pack is $99.99 for four licenses, and only the parent profile (which would be yours) can make any adjustments to the content the other three profiles can be exposed to. You would also be able to set an allowance for Microsoft points and would prevent the other profiles from adding Microsoft points online (unfortunately doesn't prevent them from entering a code from points bought in a store).
Hope that helps!
JB
