Sometimes you may have trouble booking QUP's because the phone CSRs erroneously believe that there has to be _both_ Q and A inventory available to sell a QUP. This is wrong, but a widely held misconception with the phone agents. In these cases you have to ask carefully "is there any A inventory?" and insist that they free-sell A; miraculously the QUP fare then appears even though there is no Q inventory, and the CSRs are baffled.