I got the same excuse last year (March 2015) for my Market Fare ticket, so I called Aeroplan and claim AC direct me to them

(which is what AC does say all the time) They were be able to get me some seats and I was only E50K at the time. Once I got that seats via Aeroplan, I web to the
ACO web site to re-select the seat that I want - at the time 2nd row in Y and didn't prompt for any charge. When I become SE, I call AC and have them change it to 1st row in Y.
But alc, I'm a status-peasant, I don't have your powers of persuasion.
I also tried that web site, before calling AC...no go. They know how to keep us peasants in our place.