This is amazing as I'm in a similar but different situation and came here to ask for advice - I think you've answered my question.
My situation is I am overseas and cannot find my PR book. Either I didn't bring it at all, or I brought it and its buried in my luggage somewhere. I do have the multiple entry reentry visa in both my passport and PR book so have been fretting as to whether or not that is sufficient for me to get back into the country with my PR intact in the case that I didn't bring it at all / cant locate it before I go back. From what you say I am probably OK - albeit you have your unstamped PR book and I currently don't have my PR book.
How did you get to talk to Immigration? I have been on hold for hours trying to get through to ask someone for advice.