Charge abroad

[Julie30banana]

Why was I charged to use my phone in Ireland?

[pgn]

You should not have been, @Julie30banana - unless you crossed on the ferry and picked up Manx Telecom for a short while, or sent an MMS Guide: Accidental MMS Sending and How to Avoid it 

You can contact O2 via Social Media, keep at them via Twitter DM, and you may get refunded, my experience here for example:

https://community.o2.co.uk/t5/Other-Products-and-Services/O2-Web-Top-Up-not-recognising-a-valid-O2-P...

Ways to contact O2 that way in the link below, @Julie30banana - good luck!