回复：我在美国做过wages dispute.

There is an employment standard board in Canada dealing with paying and earnings. However, my issue cannot form such a case because the bonus was not for a specific task I performed (e.g. incentive on a task of assemble a computer in half an hour). As Lao Ma said, it may be difficult to win.

(By the way I had reasons to leave in 2 days after receiving the letter.)