Anyone who has used Ryanair ('Europe's only ultra-low cost airline' as claimed on their website) will know all about being charged extra because they did not remove the appropriate ticks hidden in the small print, but 360 Euro seems like an outrageous overcharge, even if your daughter had changed her flights. There must surely be some way to appeal this. (N.B. Ryanair has being trying to take over Aer Lingus, the only serious competitor on most Irish routes, but so far the EU has blocked them. God bless the EU!)
