I'm planning a holiday for a week to Spain with EasyJet. It's much cheaper to pay for my suitcase allowance online and I was wondering how it works. What I mean is, as it is a round-trip, I have to pay twice. So doing it online, would I be charged double and is it all just a one-time payment?
I plan on going to other countries as well so it would be useful to know how paying online works and in general.