To think that if I say a month ago I'm unavailable on Thursday 7th May

[dilemma456]

Message withdrawn

Surely YANBU if you've already said you can't? How about you contact the administrator immediately and let them know? Might not have sent out the letter yet.

YANBU.

If I was you, I would 'reply to all' reminding the administrator that they were informed a month ago that you would not be available on this date and that the interview will need to be rescheduled.

YABU - you've given more then enough notice IMO!