Rail company One has "unreservedly" apologised for a spate of disruptions leading to days of commuter misery.

The rail company has said sorry for the unsatisfactory and disruptive journeys between August 30 and September 5 in a two-page letter to West Chelmsford MP, Simon Burns.

Dominic Booth, managing director of One, said in the October 2 letter: "I apologise unreservedly for the unsatisfactory journeys many of your constituents suffered over that difficult period. We understand the extreme frustration felt by passengers who did not receive enough information about the incident and the options to them."