TSR2 - sometimes if a booking is cancelled the fares will automatically be released for sale. So if someone booked the £15 tickets and then cancelled they would go back out for sale at that price unless it's on the day if departure (IE no show) It doesn't happen too often when you compare it to the number of bookings made online each day but explains why occasionally it may occur.
I should have covered this in small print - doesn't happen often that's why I omitted it. However it's not an intentional ploy to deceive customers as hampshireandy was suggesting with the wording of his post.
Hampshireandy - if Flybe are that bad why book a flight with them?
Good news on the A319 gives a bit of variety again for the ramp staff