To complain about Primary Care Services (GPs, Dentists, Opticians and Pharmacists) you should contact the Service Provider directly to address your concern informally or formally. If you choose not to you can contact:
NHS England- 0300 311 22 33
To complain about NHS providers (Hospitals Trusts, Community Services) you can raise this with the person/service involved or their manager or the Hospital Trust’s PALs service where they will try to address your concern informally or formally.
You can also raise this with NHS England or NHS Southwark Clinical Commissioning Group via the Commissioning Support Complaints Team on 0800 456 1517. If you are not satisfied, you can refer the matter to the Parliamentary & Health Service Ombudsman.