Sydney based law firm William Roberts has launched a class action against Suncorp over its alleged attempt to force wealth management clients to pay banned commissions to financial advisers.Suncorp said in an ASX filing that it would defend the proceedings, which were lodged in the Supreme Court of New South Wales last week.The legal action, which is being funded by global litigation funder - Litigation Capital Management - has been brought against Suncorp Portfolio Partners, a trustee for Suncorp-managed superannuation funds."Suncorp today confirmed that it had received a representative proceeding filed in the NSW Supreme Court against its wholly owned subsidiary Suncorp Portfolio Services Limited," Suncorp said in the ASX filing."The matter will be defended."William Roberts argues in a statement on its website that the trustee arm continued to levy volume based commissions on advice clients even though they were made illegal under the Future of Financial Advice reforms of 2013.The law firm claims that Suncorp effectively continued to collect the banned commissions from clients by entrenching conflicted remuneration in client agreements.The firm claims that potentially thousands of Suncorp advice clients are now entitled to refunds plus interest because the illegal commissions continued to be collected by the trustee business.William Roberts has invited Suncorp Super customers to join the action.The law firm said it was not targeting the legal claim at individual financial advisers working for the Suncorp wealth management business.