Rail firms have been "misleading" customers by selling tickets for services over Christmas despite knowing they will not run, a watchdog says.
Six rail companies also failed to release advanced purchase tickets for the festive period 12 weeks ahead.
Industry body the Rail Delivery Group said its members would "develop a plan" to address the complaints.
Transport Focus found more than 2,600 incorrect journeys - those already cancelled or scheduled to face disruption - on offer during the Christmas week alone.
The group also found that by 13 October - 11 weeks before Christmas - reservations had not opened on Great Western, London Midland, South Western Railway and Southern - despite regulations stating they should.
Only 15% of services were open for reservation on Greater Anglia and 25% on Virgin Trains.
Transport Focus chief executive Anthony Smith said: "Failure to release timetables 12 weeks ahead of travel can mean passengers buy tickets for trains that will not run.
"That can't be right. Train operators' advice is to book early at Christmas to get the best deal.
"But if the timetable has not been finalised only more expensive 'on the day' tickets can be bought."