Calgary with BMI? Are you sure it's not BA? BA fly to calgary and so do Air Canada. It could be a BMI codeshare flight ( through star alliance) but actually operated by Air Canada.
Regarding an upgrade, airlines always upgrade their frequent fliers first and most upgrades are done by the ground staff unless the cabin crew or flight crew know you personally! You can always ask although if its BA they will smile and mention the upgrade price !!
have a good flight and fingers crossed you get a better more comfortable seat!!
