Isn't it the reverse? (CX buys miles from BA using some of the revenue it collected from you.). I haven't really thought about this too much, but I have wondered why some programs are so much stingier than others wrt accrual.

In any event, I remain convinced that Alaska Mileage Plan is where the OP should focus his attention in the instant case. Their rules are well documented, so he merely needs to demonstrate his compliance and compel them to give him credit. Whether or not any money changes hands between CX and Mileage Plan isn't his concern.