The transport secretary insisted Boris Johnson had not checked out early from No.10 after the PM was criticised for not attending Cobra meetings.
The service's website was given a redesign that left visually-impaired passengers unable to book trips.
National Rail says disruption, caused by signalling fault, will continue until at least 8pm.
Network Rail warned disruption is likely to continue into Friday.
Tracks could buckle as the temperature soars.
“Many people living with IBS need urgent access to toilet facilities."
Damage to overhead electric wires is causing 'major disruption'.
Chris Grayling 'Totally Incapable Of Delivering Anything On Time' Amid Bungled Millennial Railcard Launch
People have branded the application process an "absolute joke".
Comedian Tanyalee Davis, who was stranded on a train, says she's very excited to trial it.