A third of complaints about hospitals are due to getting a poor apology, a new report has claimed.
The top three reasons for hospital complaints investigated by an ombudsman in 2014/15 were poor communication, errors in diagnosis and bad treatment.
The Parliamentary and Health Service Ombudsman's report revealed a fifth of complaints featured poor staff attitude and behaviour, while 10% included gripes about a mistake not being acknowledged.
The ombudsman is investigating increasing numbers of complaints, receiving 21,371 enquiries about the NHS in 2014/15, compared to 18,870 in 2013/14.
Its study found some NHS trusts were seven times more likely to be investigated over a complaint than others, which could be due to some hospitals undertaking more complex work or making greater efforts to help patients complain.
The ombudsman completed 1,652 investigations about acute trusts in 2014/15, compared to 852 in 2013/14. Its investigations resulted in 36% of cases about the NHS being upheld, alongside 44% about acute hospital trusts.
The new report shows that, on average, it investigates 6.2 complaints for every 100,000 clinical episodes in each acute trust.
Here are some of the hospitals with the highest number of investigated complaints (figures per 100,000 clinical episodes):
London North West Healthcare NHS Trust - 17
Basildon and Thurrock University Hospitals NHS Foundation Trust - 14.8
Isle of Wight NHS Trust - 14.6
Clatterbridge Cancer Centre NHS Foundation Trust - 14.5
Croydon Health Services NHS Trust - 14.1
Liverpool Heart and Chest Hospital NHS Foundation Trust - 12.4
Colchester Hospital University NHS Foundation Trust - 12.3