As has been discussed at length here, Avanti are only releasing their timetables a few days in advance. I'd booked a trip from Lime Street to Euston tomorrow before the 8th August. This meant that my seat reservation was cancelled. My train is timetabled to run so I used the change journey option, chose the same train and same seat - I wanted a single seat in Standard Premier. It cost me an additional £11.50 to guarantee the same seat that I'd booked and paid for originally. Ridiculous, and more fool me for doing this but I wanted some peace of mind.