I recently travelled from Sheffield to York. I had no seat reservation, so just picked one showing as 'not reserved'. Immeadiately in the seat next to me a conversation started, 'excuse me, these are our seats'. Reply,'someone was in our seats when we got on and the guard told us to ignore the signs and sit anywhere'. Minutes later, more passengers boarded at Wakefield Westgate. The same happened. Then at Leeds, a passenger challenged me. My reply, 'Oh! no worries. It's only another 20 minutes to York'. I was glad to stand in the quietness of vestibule end, I was sick of hearing it! If a little worried that my next journey on XC with reservations was Sheffield to Basingtoke. It went OK actually.
Root of problem: Putting a 5 car train on a service that deserves 8. And possibly lack of customer service desire on the part of XC.