When I was growing up there was a boy named Sean but everyone pronounced it at as "Seen" rather than "Shawn". No one else had a similar name in town. I ended up not realising the correct pronunciation until Yr 11 when my family moved to Adelaide. No one in my hometown had any idea it wasn't pronounced "Seen". No one seemed to mind - gotta love the English language with all it's weird inconsistencies of spelling and pronunciations.