Jonathan Attenborough has complained to ScotRail about the matter.
A guide dog owner was left to stand on a busy train between Edinburgh and Perth despite asking passengers "several times" for a seat.
Jonathan Attenborough was travelling on the 4:39pm service on Tuesday from Haymarket with his Labrador and found himself standing in the area in front of the train doors. It is unclear if he eventually got a seat or had to stand for his journey.
And Jonathan, a disability and inclusion advocate, has taken to social media to vent his anger about the lack of assistance from ScotRail staff on the service.
He said: "Completely unacceptable passenger assistance from @ScotRail to leave me and my guide dog in the doorway of the train.
"I asked several times if there was any spare seats and not one passenger responded. Doesn’t give me much faith in humanity."
A ScotRail spokesman said: “We’re sorry we let Mr Attenborough down on the high standards of assisted travel that we aim to provide. We are working hard to learn from this, and ensure that this does not happen again.
“It’s disappointing to learn that no customer offered up a seat, as we would expect customers to keep our priority seats, which are located near the doors in our trains, free for people who are less able to stand.”
ScotRail's social media team also responded directly to Jonathan and apologised that he wasn't able to get a seat.
The train operator went on to say: "Hi Jonathan, I wanted to get back in touch about your experience on Tuesday. I’ve sought advice from our Access & Inclusion Manager and also fed back to our station & onboard teams. You should have been assisted to a suitable seat, and I’m sorry this didn’t happen.
"It’s disappointing that no passengers responded when you called out, but you shouldn’t have been put in this position in the first place.
"We’re currently rolling out mandatory training outlined in the ORR Assisted Travel Policy. All new staff, including senior/key managers, will receive this as part of their induction by July 2021."
Jonathan responded directly to say: "Thank you very much for your response really appreciate it. It was an uncomfortable and unsettling position to be put in and obviously I would have expected much better service from the passenger assist team as would you I’m sure."
Guide Dogs Campaigns has also asked Jonathan is he could report the matter to their local team.
The post has sparked anger from many social media users, with Sylvia Hughes saying: "I'm so sorry that you had such bad treatment from @ScotRail and the passengers who ignored you should be ashamed of themselves. Do hope you have recovered from the journey and the experience."
@deanneoconnor40 said: "They should have made someone move for u for u to sit down, that’s what Virgintrains did for me on a CrossCountry train last week, he asked them would they mind moving from our seats, the ppl sitting there was not happy only coz they had laptops on little tables and it was busy."
Mike Holroyd said: "Hi, really sorry to hear about this experience. I travel with my guide dog on Scotrail virtually every day but on different services each day. From my experience this is very unusual - passengers are mosttly observant and staff generally attentive. Very sad to hear this."
ScotRail's Passenger Assist service can be booked in advance but customers should be able to take advantage of this whether it's been booked or not. The Assisted Travel team can be contacted at scotrail.co.uk/accessible-travel or by calling 0800 912 2901.