Zurbec, thanks for the correction on the formula. However, I think the result is: (12,000 - (12,000 x .25)) x .02 = $180
$240 would be the maximum fare premium if no flyer miles were being give, and $180 is 75% of $240. That might be a useful calculation with Hotwire, for example, which keeps all the miles.
And I completely agree with you about BA's pricing policy.