Workers on Virgin Trains West Coast are to stage six 24-hour strikes in December and January in a dispute over pay.
Members of the Rail, Maritime and Transport union will walk out on December 15 and 22 and on January 5, 8, 26 and 29.
The union said around 1,800 train managers, on-board catering staff, station and clerical workers will be involved in the action.
Virgin said it will run the majority of its services during the strikes.
Passengers between the West Midlands and London are told: "If your train is cancelled please travel on the Virgin Trains service 20 mins before or 20 mins after the cancelled train."
Manuel Cortes, general secretary of the TSSA, said Virgin boss Sir Richard Branson should meet union leaders as a matter of urgency to help resolve the row.
Phil Whittingham, Managing Director at Virgin Trains on the West Coast, said: "The RMT and TSSA leadership is attempting to cause disruption when many will want to travel by train to spend time with loved ones.
"We have explored a generous 3.6% pay increase; however, the unions' leaderships are insisting on 4%, double the 2% average increase seen across the UK this year.
"We know how important it is for friends and families to get together over the festive season, so we will keep the majority of our trains running with fully-trained staff on board and at stations.
"We remain open to talks with the RMT and TSSA, and urge them to call off these strikes which will cost their members pay for no gain."
RMT general secretary Mick Cash said: "Our members on Virgin West Coast are striking for workplace equality and workplace justice.
"All our members are demanding is a suitable and equal offer to that given to drivers to buy out their claim for a reduction in the base working week.
"We have made it clear to the company that the inequality and underhanded approach of Virgin will be fought tooth and nail. We will not accept our members being dealt with less favourably than others.
"The message needs to get through to Sir Richard Branson on his luxury island retreat in the sunshine that those who are financing his lifestyle through their hard graft have had enough and are prepared to fight for justice in their workplaces."
Drivers have received a basic pay rise of 3.2%, with an extra payment after agreeing additional productivity measures which were self-funding, said Virgin.