Complaints from British consumers increased 20% in the year to March 31, according to the UK Financial Ombudsman Service’s annual review.

The number of cases – excluding payment protection insurance issues – grew to 33,171, the most since the service launched in 2000.

Motor insurance accounted for 23.5% of new complaints, with 47% of these upheld in favour of consumers.

Non-disclosure disputes increased 60%, with the review saying many “could have been avoided if the insurer had asked the consumer clearer questions when they first applied for the policy”.

Some customers complained about confusing comparison websites, according to the review.

Motor insurance complaints grew 7% to 7785, while cases concerning commercial vehicles and property increased 24% to 1319.

Private medical insurance disputes rose 85%, builders’ warranty complaints grew 60% and pet insurance grievances increased 50%.

Complaints about home emergency cover fell 13% to 1284, contents insurance cases fell 3% to 2027 and caravan insurance disputes dropped 11% to 79.