I have sent my application for pgwp extension after getting my new passport to:
Student work permit extensions (includes co-op, internships and post-graduation work permits)
Send your application to:
Case Processing Centre in Edmonton
Immigration Refugees and Citizenship Canada
c/o Student work permits/Same employer, Station 202
9700 Jasper Avenue NW, Suite 55
Edmonton, AB T5J 4C3
I was granted work permit in just 1 month even though it was paper application. I received it on 20th arpil.
Note: Do not apply online for pqwp extension. Clearly tell about your situation that you got your work permit till passport expiry.
For any other enquiries ask me.