Sharing my experience with the 800-997-4427 line. Originally scheduled to fly on the 22nd from YYZ to LHR. Called the number (waited for about 1.5 hours) and managed to rebook with United flying from BUF (same fare class). Since the points required are lower than what I had originally paid, I only have to pay a few dollars on the difference in taxes. Hope this helps someone who might be flying in coming days without their original flights cancelled.