[Need to check and possibly update this page.]
On 1/4/09 the complaints procedure changed. There is now a unified procedure for both health and social care complaints. The first stage is to complain to the service provider (local resolution). The second stage, if still unhappy, is to complain to the Parliamentary and Health Service Ombudsman. See Local Authority Social Services and National Health Service Complaints (England) Regulations 2009
There used to be a middle stage, involving a complaint to the Healthcare Commission (and then possibly to the Mental Health Act Commission), but these organisations have been merged into the new Care Quality Commission and the middle stage has been removed. The CQC can still assist where the complainant is detained under the MHA.
Details of the complaints procedure can be found on the NHS website, and useful summaries are on the CQC website (links below).
Every Trust has a Patient Advice and Liaison Service (PALS). PALS are not part of the complaints procedure itself, but might be able to help resolve the concerns informally or explain the complaints procedure to you in more detail. You could also ask the local Citizens Advice Bureau for help.
Consultations#Department of Health. Review of NHS complaints system (15/3/13 to 30/7/13).
Complaints page on CQC website - March 2010
Clarification of Complaints Regulations 2009 - 28/1/10 - "New regulations for handling NHS and adult social care complaints came into effect on 1 April 2009 - however, some local provider websites are still referencing the 2004 regulations. Additionally, clarification has been provided on the legislative position around complaints being handled by PALS, and cases where legal proceedings are being taken."
NHS complaints procedure (DH website)
Patient Advice and Liaison Services (DH website)