Train services operated by One Rail have been severely disrupted following a 24-hour walk-out on Saturday.
The operator was forced to cancel all its Suffolk and Norfolk rural services with disruptions also affecting Essex and Cambridgeshire.
Guards and conductors walked out at midnight on Friday over the introduction of new ticket machines.
They want a "one-off" payment while they get used to the system rejecting an offer of a 1% commission increase.
An RMT union spokesperson said: "The company accepts that the machines will initially slow revenue collection, and that will affect our members' income.
"The company's offer of 1% on commission for 12 weeks is unlikely to cover our members' lost income, and means that the workforce is effectively being asked to subsidise the introduction of new technology."
A spokesperson for One said it is extremely disappointed that the RMT had taken such a stance saying: "Such a move is especially regrettable and illogical given the widespread introduction of modern technology across all businesses."
Further walk-out planned
The Norwich - London service will operate hourly to and from Ipswich and half hourly from there to the capital.
Passengers are advised to use Central Trains services and change at Ely for other routes.
Staff are also due to walk out on 7 June in a dispute condemned by One as disruptive to passengers in Norfolk, Suffolk, Essex and Cambs.