I hate spinners. You lose some valuable storage space and I find some of them are less maneuverable, due to finicky casters, than two-wheeled bags. So I wouldn't keep the bag, I would fight to get what I originally ordered.

OP, presumably you have some sort of e-mail confirmation with your order info where it clearly states what you ordered? I would keep pushing Aeroplan because if you have that backup, it's quite clear that they didn't send you what you ordered. But Aimia is an awful company with some of the worst customer service of anyone I deal with, so expect it to be a battle to get it.

I'd say your chances of getting what you actually ordered before your trip are slim to none.