Several months ago I purchased a round trip YUL-LHR flight and paid the 90$ each way for preferred seating. I believe at the time the plane was a 333, so I took one of the exit row seats. The flight is in 2 weeks. By pure chance this week, I noticed on my credit card statement a $180 credit, took me awhile but I figured out it was from Air Canada and that the only thing that it could be was the preferred seating charges. I took a look at my booking on-line and noticed I was no longer in preferred seating, likely because it would appear that there was a plane change to a 763. I quickly rebooked and paid the $180 fee, but the seatings remaining weren't as interesting as the original ones. My question is, shouldn't Air Canada advise you of the plane change and they are cancelling your preferred seating? Or maybe even rebook me into preferred seats on the new plane? I'll admit to not following the exact details of my credit card statement, but its was only the credit that advised me something was wrong. Otherwise I would have showed up for the flight and found out then -- kinda seems like poor customer service. Or am I just expecting too much?