After weeks of speculation surrounding the identity of "the merchant" at the centre of May’s bank data breach that resulted in thousands of credit card cancellations, the head of online retailer Crazy Sales has moved to fend off rumours.

No one can prove 100% that it’s Crazy Sales, said David Yin, owner of Crazy Sales, when asked directly if his company is the merchant that triggered the cancellations of an estimated 10,000 credit cards -- including 8000 by the Commonwealth Bank.