From my experiences with UA and UA.bomb, even though there are lower fare bucket listed as "9" unless it is published or available for sale on the route specified, .bomb won't sell it. Therefore, it often results in higher fare than what you would have predicted based on the availability. It seems like .bomb cannot mix fares - where I wanted to go out in H on the outbound and come back in W, .bomb always gave me H for both ways, making it much more expensive.