Use the new version of the webform (I find they tend to be a bit more responsive there than on the old version):

https://secure.cic.gc.ca/ClientContact/en/Application

When submitting your request for reconsideration, attach a letter written and signed by you on your decision to withdraw the application and explaining why and explain the urgency of the situation (by attaching the passport request letter, so they can see it's urgent).

Also, just in case they don't respond on time, contact CBSA to give them a heads up on this situation, both through phone:

https://www.cbsa-asfc.gc.ca/security-securite/bwl-lsf-eng.html

and through their online reporting tool:

https://bwl-lsf.cbsa-asfc.cloud-nuage.canada.ca/tip-sub-en.html

so the officer at the port of entry is aware of the situation and would send him to secondary examination when he arrives, for questioning, and try to avoid the COPR to be signed by the officer, granting him PR status.