You usually need to sign a tax return before it is sent to the CRA - so you would've had to sign off on this information yourself. The accountant will usually not hold any blame for submitting wrong information.
If you make a mistake on your tax return, don’t panic. The Canada Revenue Agency (CRA) is not going to rush out to your home and take you into tax custody. Instead, they have a procedure to follow that you can change your tax using tax calculator so you can change your tax return after filing and fix the mistake you’ve made.
This is a civil dispute and the CRA will not intervene. You signed on the tax return so this is your responsibility. You can use a different accountant to amend your return, and take the previous one to small claims, which, without knowing the specifics of your case, is far to be a guarantee.