Commonwealth Bank (CBA) has appointed three law firms as independent customer advocates under its review of shoddy financial advice.

Maurice Blackburn, Shine Lawyers and Slater & Gordon will support customers through the program, which is examining advice to Commonwealth Financial Planning and Financial Wisdom customers from 2003-12.

CBA CEO Ian Narev says the appointments ensure customers will have access to independent support and advocacy.

The bank has extended the review to include more than 300,000 current Commonwealth Financial Planning customers.

But contacting Financial Wisdom customers is problematic because a number are with independently owned practices.

Many Financial Wisdom advisers left the group in 2004 to join independently owned Meritum Financial Group. In 2010 MLC bought the remaining shares in the dealer group it did not already own.

Mr Narev says CBA will seek ways to contact Financial Wisdom customers who moved on with their advisers. “We will also continue to work with community groups to find other ways to contact affected customers who may not have heard about the program.”