A consumer watchdog has accused rail companies of “adding insult to injury” by blocking people on social media when they complain.

Which? said Northern rail – which cancelled hundreds of trains this week during the bungled launch of its new timetable – had been blocking passengers after they complained about the service on Twitter.

Alex Hayman, managing director of public markets at the consumer body, said: “Train companies should be bending over backwards to help passengers who have been enduring hundreds of cancellations and appalling customer service, not adding insult to injury by ignoring their complaints.”

In one example, a Twitter user called Kat Harrison-Dibbits said she had been blocked for complaining “every time [her] train was cancelled, very delayed or too full to get on”.

Hayman said Which? regularly heard stories of operators failing to engage with customers or handle their complaints fairly. “Across the country paying passengers are facing unacceptable disruption at the hands of firms that don’t seem to think their views matter,” he said. “The transport secretary must now get a grip on this mess and ensure train companies start treating their passengers with respect.”

A Northern rail spokesperson said: “We have a clear social media policy, on our website, that outlines what customers can expect from Northern’s social media team and what we expect in return.

“Blocking users is not something we do lightly and something we would never do for those who simply complain about our services. If anyone believes they have been blocked or muted unfairly, we ask them to contact our customer experience centre if they want further clarity on the decision.”

It has been a difficult week for the train operator. Northern, which runs trains across the north of England, the east Midlands and Staffordshire, launched its new timetable on Sunday but scores of trains had to be cancelled because of a shortage of drivers. The company described the change as “a significant operational challenge” and told commuters to expect disruption as the new timetable “beds in”.

There was further disruption for Northern passengers on Thursday as the RMT staged industrial action over the future role and responsibilities of guards on the train, which was set to be repeated on Saturday. So far, over 1,000 Northern services have been cancelled over the past 14 days.

David Brown, managing director at Northern, a subsidiary of Arriva UK Trains, apologised for the cancellations and delays, saying customers deserved better.

“We are introducing 1,300 new train services a week, and fitting in these and other train companies’ services has meant that we have had to change 90% of our timetabled trains. This is the biggest modernisation that the Northern railway has had for generations.

“The new timetable was planned and delivered in four months compared to the normal nine-12 months because a key improvement – electrification of the Manchester-Bolton line – has been delayed and this meant rewriting our plan and then training drivers at the last minute.”

Despite Monday being the first weekday of a new timetable for rail companies across Britain, it was passengers on Northern lines who were hardest hit. Andy McDonald, the shadow transport secretary, said this was because of a historic lack of investment in the region’s rail infrastructure.

“We’ve got to stop running train services on their bare bones, because this is what happens when you do,” he said. “It falls into crisis and then there is huge damage to the economy. Having private operators who simply look at their own bottom line is a false economy.”

The minister for transport, Jo Johnson, said the government was investing over £1bn in rail improvements and that commuters would see the benefits once “current teething problems subside”. He said the government had drawn up an action plan with Transport for the North to deal with the problems on Northern lines.

In a statement after a phone call with the transport secretary, Chris Grayling, on Thursday, the metro mayors of the Liverpool city region and Greater Manchester, Steve Rotheram and Andy Burnham, said their discussion had revealed “a considerable distance between the government’s view of this situation and ours”.

“Talk by government ministers of ‘teething problems’ suggests that these are only recent problems linked to the new timetable, when in fact Northern passengers have faced disruption over a much longer period of time,” they said. “Any solution needs to address the endemic staffing shortage in order to avoid any repeat.”

The pair said Arriva Rail North’s franchise should be removed if it failed to improve. Burnham has previously demanded an inquiry into Northern’s failing services, before timetabling troubles hit this week. “Chaos on the North’s rail network has been so extreme and so prolonged that as a company Northern have lost the benefit of the doubt,” they said.

“They simply cannot be permitted to keep inflicting a miserable sub-standard service on the hundreds of thousands of passengers across our region who have had to endure dire train travel for far too long.”