Hi,
I accidentally booked I week ahead and when I arrived at check-in they charged me 75 GBP to change the date. Fair enough, it was my fault but I still think 75 is excessive. It's not like it costs them anything.
On top of that, without any warning at check in when you arrive at boarding gate they start weighing your hand luggage and you have to pay 10GBP for every kg of over 7. I ended up paying another 70. Some passenger were just throwing away what they had bought at the duty free since they were also caught by this scam.