First-Class Ticket, seat allocated in Standard. How to change?

[Amame]

Hi Everyone. This is my first times taking train in UK so I am very new. I booked the First-Class ticket from Edinburgh to Totness thru Lner website. Today I saw the seat map of the GWR and noticed that my seats in the Paddington to Totness legs are in standard class and not first. (K48) I am unable to do any changes in Lner site for GWR train. Please advise how can I move my seat? The train timing is around 2 pm of Wednesday, is it going to be busy? I wrote them an email and they said will get back to me in 20 days, that's way too late.

Thanks a lot for your advice.

 

[Bletchleyite]

Is it definitely a First Class ticket you've got?

Can't see 2pm on a Wednesday being particularly busy to be honest and there will be unreserved seats. But there are a few ways to get a reservation.
1. Sign up for an account on gwr.com, and under "My Account" there is an option to reserve seats, though unlike LNER there is no seat selector so you get one at random.
2. Go to a booking office of any TOC (may not be possible if you're in the UAE )
3. Contact GWR customer services and ask them for one. Twitter/X may be the best bet for this.
4. Just show up and take the risk, at that time it should be fairly quiet. The reservations don't work on GWR half the time anyway.

Actually, scratch all that. Coach K, Seat 48 is First Class on a 9 car set, @Amame I think you must have been looking at the plan for a 10 car. It's a window side table seat facing the direction of travel on the 2 side.

9 car plan: https://www.seat61.com/reference/trainseatplans/GWR-IET-9-car.pdf?dl=0

 

[jfollows]

Agreed, the 14:03 departure from Paddington today is a 9-car set and coach K is First Class.

 

[Amame]

Thank you so much @Bletchlayite and @jfollows for looking into this for me. Very kind of you!
Yes, I was looking at the 10 cars set seat map as it is the only one I could find on google.