This is a good bible but, at 230 pages, don't try and read it cover to cover!
It is published by the Disability Rights Commission in 2004 so it includes legislation that was changed in about 2003. Look at the Contents Pages to get the gist of what it covers, then dig into specific pages, perhaps to understand how the requirements of the Act are typically implemented. Not all of it probably applies to your type of employer.
http://83.137.212.42/sitearchive/DRC/pdf/4008_323_employment_occupation_pdf.pdf
This sounds like a public sector job promotion to me? - it's typical of the sort of anal reason a public-sector employer would give for failure to progress at a job interview.