Told to move from unmarked reserved seat...

[Joseph_Locke]

No, the customer buys a ticket to travel.
Their ticket does not stipulate they will get a seat, or even that a train is involved.

Or, if my understanding is correct, at any specific time of arrival or departure other than outward travel on that day (sometime).

 

[Greybeard33]

Try Transport Focus. They might not budge, but at least you get to waste a bit of their time.

Thank you for this sound advice. Following my complaint to Transport Focus, I have now received a cheque from TPE that refunds 50% of the price of our single tickets from Edinburgh to Manchester, in compliance with the wording of the TPE Passenger's Charter. Even though we only had to stand between York and Leeds.

 

[Greenback]

Thanks for letitng us know the outcome.