I have become frustrated trying to book a short-haul military 'friends & family' ticket today. The T&Cs clearly state that short-haul flights have no requirement for a Saturday night stay yet when I tried to book a mid-week return on flybmi.com it would not proceed, giving an error message stating it requires a Saturday night. This particular route is available for economy or business ticketing.

I rang the ICC and explained the problem, only to be put on hold repeatedly (call took approx 40 minutes, long distance since I'm abroad) and end the call with no ticket. Here is the sequence of excuses I got:

1-HM Forces scheme does not have business fares on this route, they can only ticket economy
(I directed them to the section of flybmi.com that explicitly states the business fare applicable to this route)
2-Business Class is completely sold out
(I told them the F&F section of flybmi.com is showing availability in business on that route for the entire week)
3-We cannot price the ticket possibly because of the Saturday night stay
(I referred them to Sec.2 of the T&Cs stating it is not required)
4-They don't know the fare basis
(I gave them the fare basis, fare and taxes which I was able to get by making a dummy booking with a Saturday night stay whilst on the phone)
5-They can only ticket me today in economy (back to excuse #1) otherwise I would have to wait until later in the week until its resolved (violating the 7 day AP required for the dates I require)

I then asked how it is they are able to ticket the exact same flights in economy and not business if it is the Saturday night stay that prevents pricing. I got no clear answer, only that they could. I then asked if I booked online with the Saturday night stay if they could change the return to my original date, they were not clear what they would do but said in any event they would charge a change fee irrespective of their 'inability' to book it.

Does anyone have some advice/experience that might help me sort this out?

It seems like BMI's call centre is basically trained to stop potential customers from using an entitled discount or DC miles to travel in a premium cabin when it is available, even if it means initially lying to the passenger to get them to settle for an economy seat.