Ok, heads up, just did the PM with OM and they applied the PM before the coupon (I used 15$ one to be sure). The key was to call for PM AFTER delivery, cause only after delivery they charge your card and before they cant refund you, since there was no charge yet. I also suspect that they can no longer see the coupon after the charge was made, something to do with accounting issue, coupon is probably going into the marketing expense, and the whole price is being credited to their bottom line. So there you go, call for PM after delivery and your chances are good.