that might be a good way to end any future relationship with BOA. and, if you read the fine print that came with your card, you might also find yourself on the hook for some dollar-assessed cost of those miles you already spent...so while they might not claw them back, they might bill you. i'm speculating--you have the actual contract. read it
i'd say call and ..... about the bait-and-switch on the card and how you're strongly thinking about canceling because of that. maybe you can net yourself something worthwhile retention-wise.