Hi ilovecanada1973,
Thank you very much for sharing your experience. I have exactly the same issue here and it was comforting, though the situation is massively annoying, to know that someone else was going through the same.
My time line was very similar to yours - I received my first letter in mid Aug and the appointment to pick up my PR card was scheduled in the end of Aug. I am studying abroad at the moment, and it was such a short notice for me to drop everything and fly back to Canada (e.g., applying for a Travel Document etc), thus I missed my first appointment. I have contacted the IRCC through their web form twice to let them know that 1) I wouldn't be able to make it to the appointment; and 2) how I could reschedule my appointment. I haven't heard anything from them since Aug other than having received the acknowledgement email of my questions.
I understand that all what we can do is just to wait, but it is quite unsettling not knowing when the appointment will be and whether the next appointment will be scheduled within 180 days as they state. I have my Travel Document now so traveling back to Canada won't be a problem other than a obvious cost of flight.
Anyway, I hope you hear from the IRCC shortly and that everything goes back to normal as it should be. Please keep me posted. Thank you again.