Great Western Coffee Shop

Somewhat surprised this hasn't been mentioned yet, given the signalling issues on the other route from Oxford to London

https://www.bbc.co.uk/news/uk-england-oxfordshire-66299823

You'd expect transport companies to at least have a maintenance contract with the control panel manufacturer, wouldn't you?
Repair within 24 hours? It's a vital piece of kit.

Unless it's another ruse by their paymasters to cut costs.....

Travelled from Oxford to Haddenham on Tuesday and service reduced to one per hour. Even worse on the way back as there were no trains to Oxford scheduled to call! Had to get a lift back to town  :(

I could have tried doubling back through Princess Risborough - was my ticket valid?

I couldn't travel via Banbury as my ticket was Chiltern Trains only.

They have come down a long way since their heyday.

If they weren't stopping services to Oxford at HDM, then yes doubling back must be permitted. You have a contract with them to be taken to Oxford.

They possibly will have a support contract at the very least and may well have a maintenance contract and include breakdown call out, but the fault can range from a blown fuse to a catastrophic failure involving a rebuild

I am always wary of the headline statement in the media these are often simple statements and do not give the detail of what the actual fault is

It's unfortunate (but presumably not connected?) that they chose the same day to send out a press release about using "Hydrotreated Vegetable Oil" in their Class 68 locos.  They seem to have got away with it and the diesel fuel problem doesn't seem to have been splashed over all the HVO reporting.