Flybe have not increased prices. They have simply responded to seasonal demand. The summer flights have been on sale for some time now and it is likely that any lower fares have now been purchased. Yes some increases have come into play but this is simply because flights are already busier.
I think you'll find that most airlines have not directly put fares up, they have simply restricted the number of available seats at the lower rates. Check Flybe's/Air Southwest's website as these list the lowest fares on each route.