What rule or regulation does one quote if refused?
The National Rail Conditions of Travel. And if there's a refusal to help then you pay for transport/accommodation out if your own pocket and then complain. When the complaint is not upheld/ignored you then sue for breach of contract. When the
TOC▸ then fails to turn up in court you get a default judgement. When the TOC doesn't pay, you send bailiffs to their head office. There's a recent precedent.
Oh, and not forgetting the Consumer Act 2015 allows you to seek damages as well as your claim and costs.