My wife was due to travel from Wakefield Westgate to London on Saturday on an advance ticket. Now she is trying to change the ticket for free to the following Saturday 2nd July as LNER is supposedly allowing. However just about all the trains say 'sold out' even though advance fares are still available on them if you try the normal booking process rather than amending the journey. Any ideas why LNER's app and website are not allowing her to change the ticket?