What date/time is it for?
There's not much you can do,
unless the company states that it is cheaper the earlier you book; it really depends on what they are advertising at the time the ticket is sold.
Edit: I think you may a case under consumer law; LNER state this:
Cheaper tickets, same great journey. Book further in advance on the LNER website and app than anywhere else.
www.lner.co.uk
An Advance ticket is a single ticket for a specific train that you book in advance. There's a limited number of these tickets on any given train and the earlier you book, the cheaper the tickets will be!
Which is very clear that your price should not be going down.
But when you continue reading, they go on to contradict themselves:
What are the advantages?
- They’re usually our cheapest fares*
- You can combine different types of single tickets to save money
- You get an automatic seat reservation
- You can book at least 12 weeks before you travel for most dates and routes (see current exclusions)
- Or you can buy Advance tickets up to 5 minutes before the train starts its journey, meaning you can bag a bargain on the day.
*Prices normally increase closer to travel, however, occasionally prices may go down, for a variety of reasons. An example of this is if there is a seat sale.
It's not clear to me what the position should be, where such a contradiction occurs, though in general any contradiction should be resolved in favour of the consumer, not the company.
Do we have any lawyers here who are experts on contract & consumer law?