Finally got there after manual intervention from the ticket office and 15' on the phone. Also told that the seats I wanted were all full rate, no child discounts due to location. This wasn't what the website said during my failed attempt to book online, fortunately the ticket office let me...
Trying to get Burnley Tickets sorted but it keeps telling me that there is a problem with card validation when I come to check out and I know there isn't at my end.