If you believe that your treatment under the NHS has been substandard in any respect, it is your right to make a complaint.
Your concerns may relate to the quality of care you have received, or they may be to do with other aspects of the way in which your treatment has been handled (for example, you may want to draw attention to unacceptable delays in your treatment, or a poor standard of communication on the part of your doctor).
The NHS states that it wants to hear your complaints. Learning of your concerns should help them to do things better in future. It is also worth knowing that the efficiency with which NHS Trusts handle complaints is one of the criteria on which they are judged, as part of the "NHS Performance Ratings". As a result, each NHS organisation has an interest in making sure any complaint they receive is handled sensitively and professionally.
The NHS Complaints Procedure is laid down by the Department of Health. Although there are differences in how various NHS organisations run their complaints procedures, the same basic stages apply throughout the UK. It is a process with up to three steps, which you have to follow in turn.