MPs have called for an overhaul of the "outdated" public services watchdog to help prevent repeats of the Staffordshire hospital scandal.
The Parliamentary and Health Service Ombudsman should be transformed into a more responsive "People's Ombudsman" with tougher investigative powers, according to the Public Administration Committee.
The report said individuals should have the ability to complain directly to the new-style watchdog about the NHS in England or government departments, rather than having to go through their MP.
The ombudsman should also be allowed to receive complaints in person or online, instead of solely in writing as is currently the case, and initiate its own probes into areas of concern.
Committee chairman Bernard Jenkin said: "PHSO is part of our service to our constituents, and it's way behind the times.
"Our voters have a right to complain about public services when mistakes, misunderstandings and maladministration occur.
"We so often see that people complain not for their own benefit, but to ensure lessons are learned and the same mistakes are not inflicted on others.
"As we recently reported, the disaster at the Mid-Staffs hospital is a tragic example of what happens when the complaints system does not work.
"As Dame Julie Mellor has put it, there is a 'toxic cocktail' in respect of Government's complaints handling - a combination of the British reluctance or the inability to complain and a defensive rather than receptive attitude in public services - that is poisoning efforts to improve public services.
"An effective ombudsman service can help bring about the change in attitude, behaviour and leadership that we need.
"Complaints must make a difference. Complaints should be welcomed and used to help to improve public services for everyone.
"Our conclusions are aimed at creating a more effective People's Ombudsman that better serves the public and can be part of a modern approach to delivering excellent public services.
"It is up to Parliament to change the legislation, so we are looking for a commitment from government to get it done."
Which? executive director Richard Lloyd said: "People often don't speak up when things go wrong in public services because they don't think anything will change, but feedback is vital to help improve services. When complaints are unresolved it's even more important there is an effective and proactive ombudsman to give people confidence that complaints do count.
"We've been calling for a unified public services ombudsman to act as a one stop shop and deal swiftly with issues raised. We hope the Government now acts on these proposals and makes it easier for people to voice their concerns, which will help prevent the same things happening again."
A Government spokeswoman said: "We are committed to improving public services. The tragic events at Mid Staffordshire were a turning point for the NHS and the Francis Inquiry showed just how important it is that there is an open and transparent culture where complaints are listened to, and action is taken to improve services - we are committed to taking this vital agenda forward.
"We welcome PASC's work in this area, and will respond to the committee's report in due course."