I'm booked in an AC flight from YYZ to MAD in Premium Economy that leaves tomorrow night. My long booked aisle seat is now showing up as a middle seat. Phone rep at Air Canada says there's nothing they can do as no other seats are available.

Needless to say, I would not have booked a cross-Atlantic trip in a middle seat -- I would have booked another airline first. (I did try to bid on an upgrade to Biz beforehand but was rejected at $800 -- they now want over $3K for an upgrade to Biz.)

EDIT: I tried calling Air Canada again and a more helpful rep was able to see that my aisle seat was canceled the same day I put in my bid to upgrade. I would not have thought that offering to pay Air Canada more money resulted in a worse seat, but there we are.

What are my options? Does anyone with experience think I'd be better off trying to get an aisle (or window) seat in regular Economy? Or is PE worth spending 7 hours in a middle seat? Is it worth trying to get compensation?