as far as I remember after multiple attempts to contact immigration by phone she was able to get a hold of an agent and explained a mistake was made on her PGWP. This agent put her in contact with another person from the Windsor POE and called her to confirm that a new work permit was going to be released for her at that border. We drove to pick up the new one.
All this was in 2019, I believe it's not possible to flag pole anymore due to Covid19. Maybe try to contact them by the online web form?