I was having a think about this before and maybe, just maybe if you were to take the body (+lens) to an independent reputable camera repair facility and get them to verify in writing that a problem exists that you might then be able to go to the ACCC armed with Canon's report saying there is nothing wrong and
the independent repair places report saying there is a problem and seek some sort of satisfaction along the lines that the camera is not fit for sale as it doesn't work as expected.

Possible?