By james art 
There is also “little evidence” that complaints made to the health service are used to improve services, HealthWatch England said.
It comes as a survey showed that more than half of those who made a complaint to the NHS organization were not satisfied with the process or the outcome.
The survey of 2,650 adults in England, carried out by YouGov for HealthWatch, found that almost one in four (24%) had a bad experience with the NHS in the last year.
However, 56% of these people took no action, with less than one in 10 (9%) making a formal complaint.
Of those who did not formally complain about their experience, around 34% said it was because they did not think the health service would use the complaint to improve care.
A third of people said they did not think NHS organizations would respond effectively, while a fifth said they were worried that a complaint would affect their ongoing treatment.
About 19% of those who experienced poor care did not know how to complain, the survey found.
Of those who complained, around 56% were unhappy with the process, with the same proportion unhappy with the outcome.
Louise Ansari, chief executive of Healthwatch England, said: “We know that public satisfaction with the NHS is at an all-time low, with too many patients receiving poor care.
“When patients feel their complaints are not being taken seriously or are not being acted upon because of a complex system, services are missing out on vital information to help them improve.”
Figures published in October showed that the total number of all reported written complaints in the NHS in 2023/24 was 241,922, a 5.4% increase on the 229,458 reported in the previous 12 months.
However, the HealthWatch report claims that “low public confidence prevents people from taking any action after experiencing poor care”, meaning that current complaint numbers “may just be the tip of the iceberg”.
He added that “there is little evidence that complaints are systematically used to improve care”.
HealthWatch analysis shows there was a 37% increase in complaints between 2013/14 and 2023/24.
It suggests this could mean people are more confident in speaking up as more organizations adopt NHS complaints standards introduced in 2022.
However, he also argued that the rise could be “driven by the poorer quality of care caused by the pressure on the NHS, particularly since the pandemic”.
“Despite the year-on-year increase, the health service may not have learned from complaints and remains in a cycle of repeating the same mistakes,” the report said.
Ms Ansari added: “We highlighted the failings with the NHS more than a decade ago, following the patient safety scandal at Mid Staffordshire Hospital.
“Ten years of our research shows that the public still has no confidence in the NHS complaints system.
“We need a step change in the way people’s complaints are handled and acted upon. Healthcare leaders need to focus on developing a culture of listening and learning from complaints across the sector.
“Making it easier for patients and families to navigate the complaints system through the NHS app, setting mandatory response times and measuring people’s satisfaction with the complaints process and outcomes will be a key part of this.”
An NHS spokesperson said: “Every patient deserves high-quality care and NHS staff are working tirelessly to respond to the growing demand for services – with record numbers of patients seen in both primary care and hospitals over the past year.
“The NHS takes patient experience very seriously and we are committed to listening to patients and rolling out initiatives like Martha’s Rule, which are already having a transformative effect in some cases.
“This report highlights that there is still more to do to listen to patients, respond to complaints and improve services, which is why the NHS is working closely with the Government on this year’s 10-Year Health Plan to help us transform services to provide the Best quality patient care. “
A spokesman for the Department of Health and Social Care said: “This report shows that the NHS complaints system is failing too many patients.
“We are determined to foster an environment where patients and NHS staff are able to speak up, knowing that they will be supported and that their concerns will be heard and acted upon.
“We must never turn a blind eye to failure, which is why we will build a culture of transparency across the NHS and ensure that patients’ voices are heard.”
Isabel Lowca, director of NHS provider policy and strategy, added: “Listening to patients and their families is a vital part of delivering a safe service.”