A rail firm that only runs seven services a day is the most complained about in England, it has emerged.
Hull Trains has been dogged by problems, with its fleet of four trains suffering a series of breakdowns.
The firm received 261 complaints per 100,000 journeys between April and June this year, according to official data.
Its rate of complaints soared by 60%, while Northern and Govia Thameslink Railway (GTR) suffered an increase in complaints of 63% and 23% respectively.
Complaints soared during chaos caused by new timetables earlier this year, according to data from the Office of Rail and Road (ORR).
Hull Trains managing director Louise Cheeseman has previously said its trains were 18 years old and did 1,000 miles a day.
A spokesman said on Friday the newly revealed figures were "disappointing".
"Clearly, we let our customers down during this period and we are very sorry that this was the case," he said.
"The number of complaints we received in Q1 2018-19 follows an unavoidable and challenging period of service reliability associated with train faults in the aftermath of the Beast from the East.
"As the UK's smallest train company, we need four trains to fulfil our timetable. Three of our trains were damaged during this time and, as a consequence, we were forced into operating a contingency timetable."
He said the firm had since invested £60m in five new trains which will be delivered next year.
"These state of the art trains will be some of the most technologically advanced and modern on Britain's railways - improving our services further and giving us greater resilience during service disruption."
The operator was ranked above Grand Central, which received 227 complaints per 100,000 journeys, and Virgin Trains West Coast, which received 191.
According to ORR, punctuality and reliability remain the most appealed about complaint category.
This was followed by complaints about facilities on board and the lack of room for passengers to sit or stand.
The regulator said long-term there had been a decline in complaints since 1998-99.
It said a number of operators had experienced a higher proportion of complaints about timetabling in this quarter compared to the same time last year.
Journeys on GTR and Northern were particularly affected.