Here is a very scary thought and one law firms can avoid if they keep in constant communication with their clients and seek feedback on their services. Fast Company talks about the culture of complaint, and a Harvard study on handling complaints. This study could be helpful for law firms in dealing with complaints from clients, but first they must be communicating with clients and getting feedback.
Fast Company’s article includes some complaint web sites. I am unaware of any sites for complaints against law firms, although some probably exist. The scary part is that it could happen to law firms and no one will want to see their firm’s name appear on one. That’s bad marketing! So, talk with your clients constantly about what and how the firm is doing.