In a submission to the Senate Economics References Committee Scrutiny of Financial Advice inquiry, the bank addressed issues raised after a joint Fairfax Media and Four Corners report highlighted instances of claims mishandling within CommInsure.
CBA said those reports do not represent an "accurate reflection" of its culture and ethics.
"We do not tolerate behaviour that could put the financial wellbeing of the customers, businesses and communities we serve at risk. To date, we have not identified any instances of malicious staff misconduct which has led to the decline of a claim," the submission stated.
The bank also rejected allegations that whistleblower Dr Benjamin Koh was fired for raising concerns about business practices.
"Dr Koh was dismissed for serious and repeated breaches of customers' privacy, involving highly sensitive personal, medical and financial information over a lengthy period of time. His statements and associated conduct during the investigation of his breaches were also misleading," CBA said.
"The investigation found that Dr Koh sent around 230 emails, attaching a total of around 260 documents, to his personal Gmail account. The emails were unencrypted and included sensitive customer files, medical reports, financial information and CommInsure corporate information."
As for accusations regarding the destruction of medical documents, CBA said it has not found any evidence to support this.
"Based on investigations at the time, we did not find any evidence of medical files being intentionally deleted or tampered with resulting in missing information, as has been alleged," the submission said.
The bank, however, admitted "it could have done better" in other areas, such as updating definitions. It said it has accelerated an upgrade to its heart attack and severe rheumatoid arthritis definitions in its trauma product.
About 100 customers since 2014 are expected to benefit from this update.
"The product disclosure statements relating to these definitions for new customers have now been updated and coverage has been backdated and applies for all claim events from May 2014 onwards," CBA said.
"May 2014 was the date of the last relevant product disclosure statement for the trauma product. On the basis of actuarial estimates, we expect up to 100 customers will benefit from the backdating of these upgrades."
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