Exactly what Andy said.
I don’t doubt there are big issues getting stock and staff in the right place. Maybe it’s even impossible.
When a train fails on Saturday morning, I DO find it unacceptable that even if all spare options have been exhausted within CS’ fleet, that GBRF are unable to move stock to the correct locations (are they doing this ? - the service alterations page suggests starting from Edinburgh) that no other train, locomotive or coaching stock can be driven by any other company or agency (albeit route conducted) anywhere in the UK, and you have to resort to sending a bus from Euston to Dumbarton, for a train departing almost 36 hours later.
Some people in this thread seem to want to say any reasonable alternative plan is unachievable, and we just have to accept such things. For a target market that is moving increasingly from being a form of travel into the selling of an experience, at a huge premium against simple day travel, the review sites and the social media, critical to communicating with international visitors, paint an increasingly bleak viewpoint. Serco and government ministers need to act fast to salvage this situation.