Make sure that you know your rights well by consulting the section What the Act says.
Clarify the situation and, wherever possible, resolve the problem.
This approach often makes it possible to settle the problem and to avoid having to file a complaint with the Commission des normes du travail. It is in your interest and that of your employer.
If you prefer to write to your employer, this model letter (Word, 24.5 Ko) can help you inform him of your concerns.
If necessary, get in touch with the Service des renseignements for more information. If the steps taken have not produced the desired results, file your complaint as soon as possible to avoid losing your rights.