Flightmapping - I think it's down to the individual to contact their Credit card companies, I know someone who has done that and is expecting a partial refund that way.
Don'doit - I think you are the one who is confused about low costs, although the term is somewhat misused. The term low cost was coined in the US when Southwest was able to demonstrate considerably lower Operating Costs per ASM than its mainline competitors. On the basis of its low costs it was able to make profits with substantially lower fares. Although the average traveller thinks low cost means low ticket cost that's something different. As for Duo - I do not think that operating 50-70 regional jets will get you to the level of operating costs per ASM or ASK as easyJet - although Flybe claim they get there with the Q400. Not only would Duo's costs have been higher but they had an unusual fare structure which offered low fares with no extras plus high fares with some non-flight based extras (taxi service within a certain radius of BHX, lounges etc) at the same time. Coupled with poor or confusing advertising they were struggling to get their loads up. Perhaps if they'd been given the summer they may have made it, but it required more investment which it seems was not forthcoming.