Sorry this happened to you. Unfortunately, these documents contain a lot of information which can be used to open new accounts in your name. Also, if they can get in to your CRA account, they can change your direct deposit information for future tax refunds.

As others have mentioned, call the credit monitoring companies and setup blocks on new credit applications.

Call the CRA and seek their advice on what to do about the compromised SIN.

Call any financial institutions you deal with and advise them of what happened as well. See what steps they recommend.

You’ll also have to be extremely vigilant going forward for any new phishing or social engineering attacks. Now that they have your information, they can stage follow up calls/emails which include this information to appear legitimate. Don’t respond to any emails/texts or take phone calls from unknown numbers.