It happens, and it's usually easy to fix if you act quickly.
Before your tickets are issued, you can change it yourself, free of charge, in Manage booking. Enter your booking reference, departure date and surname, then choose another station on the same journey, at the same ticket class and price.
After your tickets are issued, or if the station you want isn't available, email the reservations team with your booking reference, the station you selected and the station you meant, and we'll move you if there's space. An amendment charge may apply depending on how close to departure you tell us (see Can I change my booking?).
Your travel documents are issued for the station on your booking, so please check your confirmation as soon as it arrives.