In the 2013 report, Lawrence Tomlinson accused RBS of systematically wrecking viable businesses.
And in 2014, RBS deputy chief executive Chris Sullivan told him he would have to take his mortgage, business and personal accounts to another bank.
But RBS said the decision had nothing to do with the critical report.
Tomlinson’s report accused RBS of using questionable property valuations to artificially downgrade viable businesses.
He said the businesses had then been moved to the bank’s Global Restructuring Group (GRG), which had charged extra interest and fees.
RBS denied GRG had treated customers unfairly. It commissioned its own inquiry, which rejected the main allegations in Tomlinson’s report.
But last June Sullivan sent an email to Tomlinson telling him to move his mortgage and all his bank accounts.
It said: “In view of your longstanding dissatisfaction with the bank, we have concluded that the required trust between you and the bank has irretrievably broken down.
“For that reason, we have concluded that we cannot continue a banking relationship with you either in a personal capacity or a corporate capacity.”
The bank eventually backed down over the mortgage on his home, but Tomlinson had to find new bankers for his business, which employs more than 2,000 people.
He said: “I’ve been with them 20 years. I’ve tried to help them change, and they’ve cancelled all my business and personal accounts – I think to just create the maximum amount of disruption to me and my businesses”
But RBS said trust had broken down because of a long-running dispute over a complaint Tomlinson had made in early 2012. It said two investigations into this complaint had found no evidence of wrongdoing and that Tomlinson had failed to attend a meeting to discuss the findings.
The BBC’s Panorama programme has also spoken to business people who accuse Lloyds Banking Group of using similar practices to those outlined in Mr Tomlinson’s report.