https://www.slab.org.uk/faqs/what-if-your-complaint-is-about-a-solicitor/
If your complaint concerns the service provided by your solicitor, including in the Public Defence Solicitors Office, the Civil Legal Assistance Office or the Solicitors Contact Line, you may also make a complaint to The Scottish Legal Complaints Commission (SLCC). This is an independent body set up by the Scottish Government to investigate all complaints about the service of the legal profession.
You can contact the SLCC: