The best way for you to correct the mistake would be to file an adjustment.

Here’s how you file an adjustment:

1. Wait until you receive your notice of assessment from the Canada Revenue Agency (CRA).
2. Once you’ve received your notice of assessment, visit the page How to change your return on the CRA website.
3. Follow the instructions on the CRA website. You can change your return online or by mail.

• If you choose to amend your return(s) online, the processing time is approximately 2 weeks.
• If you choose to amend your return(s) by mail, the processing time is approximately 8 weeks.

I have the same problem but I did not think it an employer mistake. The PA number is a result of my pension transfer from another employer and it created a negative RRSP contribution room on my Notice of Assessment from CRA. There is no way in TurboTax to enter this negative number.

You cannot enter a negative amount for RRSP. If there is an over-contribution from the prior years that has been covered by your new income, you will have to address it by withdrawing this amount or otherwise, you will be subject for penalty: https://www.canada.ca/en/revenue-agency/services/tax/individuals/topics/rrsps-related-plans/contribu... 

You either submit a T3012A form to CRA requesting the withdrawal, then submit this from to your RRSP financial institution:

https://www.canada.ca/en/revenue-agency/services/tax/individuals/topics/rrsps-related-plans/making-w... 

Or you withdraw the excess amount from your RRSP, obtain a T4RSP from the financial institution, then complete a T746 form:

https://www.canada.ca/en/revenue-agency/services/forms-publications/forms/t746.html

If you still have issues after following this process, please contact our support line:  https://support.turbotax.intuit.ca/contact/

I hope this was helpful