Write what you want to be read. Do not write “ACCC” if you want to say “Australian Competition and Consumer Commission”. When you abbreviate, write what you want to say so “ACCC” becomes “A-triple-C”.
Even if the newsreader has previously used the full name, you cannot expect a listener who is unfamiliar with the abbreviation to remember what the letters stand for.
If you refer to the “Australian Competition and Consumer Commission” first by its full name, and later as “the commission”. In some lengthy reports you can repeat the full name towards the end of the story, so listeners who have not grasped the name at first mention will not be left in doubt about what commission you are talking about.
Repetition is far more important in broadcast writing than writing for print. If the abbreviation is an acronym it should be written in caps with a pronunciation following, such as “ATSIC (pron. ATT sick)”. If an abbreviation is to be read as initials, it should be hyphenated, such as “U-N”.