Other transport or overnight accommodation has to be offered.
I wonder if telling people they should have turned up two and a half hours earlier and caught the previous train constitutes an offer of other transport? Even supposing they can get in touch to be told ...
And in any case they've just cancelled the previous one that they were suggesting ... so the last Swindon to Westbury of the day has already left!
The 17.18 has just left Swindon for Westbury, so perhaps staff made it to work after all!