Making a claim to an insurance company can be worse than the distress of the original incident, according to Which?, as it launches a rare type of action against the sector.

The group’s super-complaint – which is an action by a consumer body on customers’ behalf – says the home and travel insurance sectors are “broken”.

Which? highlighted cases including an insurer initially refusing to pay out for a cancelled holiday, because the trip had technically started before the flight was turned back after two hours.

The insurers’ trade body said providers worked hard to help customers, handle claims efficiently, and had paid out many millions of pounds.

Rocio Concha, director of policy at Which?, said that serious failings in the travel and home insurance markets had been “tolerated for too long” by the insurance industry and the regulator, the Financial Conduct Authority (FCA).

“We have heard heartbreaking stories from people who have found the experience of dealing with an insurance company worse than the distressing life events that led to their claim,” she said.

She added that a super-complaint was “a major intervention”. Such a move is rare, and only used by consumer advocates when they believe a large number of consumers are being significantly harmed by practises across a particular sector.

Millions of people across the UK take out insurance policies they hope they will never need to draw on.

Estimates suggest around 30 million people have buildings and contents insurance, with a similar number buying either annual or single-trip travel cover during last year.

Which? said that 99% of car insurance claims were upheld, but acceptance rates fell to 63% of buildings insurance claims and 80% of travel insurance claims.

It pointed to the case of Yvette Greenley, whose flight from Luton to Egypt was sent back owing to technical difficulties.

Mrs Greenley said the problem with the flight and a lack of alternatives meant her holiday to celebrate her 60th birthday with her sister, Beverley, was over. She cancelled her leave and went back to work.

While the airline refunded the cost of the ticket, the insurer initially refused the £140 claim for accommodation and travel to and from the airport because the holiday had begun.

“I was flummoxed, then fuming about it. They seemed to dismiss the fact that the plane turned around,” she said.

The insurer later apologised, settled the claim and paid compensation.

In recent years, BBC News has reported cases including:

Analysis of cases, in addition to surveys and research by Which? have led to the super-complaint that, by law, requires a response within 90 days.

The complaint is based on three areas of concern. The first is the way that claims are handled, with many being outsourced by insurers to specialists.

The second is the sales practices of insurers, which the consumer group argues are inappropriate and lead to widespread confusion over what is covered in a policy.

Finally, it accuses the FCA, as the regulator, of failing to provide an appropriate degree of protection for consumers.

It has received support from James Daley, managing director of independent consumer group Fairer Finance.

“The FCA has only recently finished a number of studies looking at this market – and while it acknowledged a number of failures, it seems to have no appetite to tackle these,” he said.

A spokesman for the FCA said it would respond to the super-complaint in due course, but had been “focused on raising standards”.

“We uncovered issues when we recently reviewed insurers’ home and travel claims handling. We’ll be holding them and their senior managers accountable for the changes needed,” he said.

They included issues over outsourcing and storm definitions.

The Association of British Insurers, which represents providers, said that its members worked hard to ensure customers knew the details of policies and handled claims as quickly and efficiently as possible.

“In the first half of this year alone, insurers have paid out over £1.7bn for more than 300,000 home insurance claims. Last year, travel insurers also paid out £472m across more than 500,000 claims,” a spokeswoman said.

“We’re working closely with the regulator to ensure good outcomes for customers and will engage with Which? to understand the details of its concerns.”