Bus Eireann same day return instead of 30 day one

Long story cut short: my mind was acting up this morning, meant to book a 30 day return ticket on Bus Eireann and ended up with a day return. (Set starting date and both times but left the returning date out. After the booking has gone through noticed the mistake.)
There is a manage your booking option on website, no luck, throwing me Only reservable route can be changed error. Mad!) Travelling tomorrow, p1ssed off with myself. What can I do? (The website should give a warning asking whether you want to return on the same day.)
Thanks!