Ryanair sharp practice

melb

I am a big fan of Ryanair and use them several times a year.  In July I booked flights to Spain at the beginning of September, knowing that i could transfer them free of charge if necessary.
I have decided to pt the flights back to October in the hopes that things will have changed by then. 
I looked at the prices of flights and found some that were £15 less per person than I had originally paid.  Went to 'manage my booking' to change to these dates and lo and behold it was going to cost me over £21 for 2 people to change to these flights - the flight prices bore no relation to the ones I had seen.  Went back to check and still got the same lower amount.
Have just been onto live chat and been told that they are 2 separate systems and the system will find prices the same or higher than the ones you originally booked.  I asked the question so in that case why does Ryanair say that if the new flights are cheaper than the original ones, there will be no refunds.
I put this to the lady but it was like talking to a brick wall.  At least she changed them for me for £10 so saved a bit.
Ryanair seem to be hiding their transfer fees by upping the cost of flights when you actually go to change them.  I am assuming a lot of people would just go into manage my booking and change them rather than comparing the price to what you would pay if you were doing a new booking.