I have found it cheaper on many occasions to buy a ticket rather than use frequent flyer points. The most recent example of this was a BA LGW-GLA return ticket. I wanted to use Airmiles but if I had done so the "taxes" came to more than the BA.com ticket I subsequently bought (which included "taxes"). As a lawyer I am beginning to think it is time to have some legal fun with this by making a report to local trading standards people, and/or to the Office of Fair Trading and perhaps throw in the CAA, the EU Commission and maybe even the Dept of Trade.