Back in mid 2017 (at least), CASA used to have a publicly available document. Service Charter of the Civil Aviation Safety Authority from Executive Manager, Corporate Affairs. Copyright date 2001.
You could back then find it easily just by googling that title. Google it now and be spellbound by what you find.
Page 12:
If you write to us, we will:
■ provide a written response to you as soon as practicable, but within 14 days of receipt, or
■ in the event that this time limit cannot be achieved, we will send you an interim reply explaining why and telling you when we will provide you with a full reply.
and
If we do not meet our stated standards or service levels, let us know. We will try to resolve your concerns internally, but if this is not possible, we will let you know the various avenues of redress that are available to you.
I don't know when but this Service Charter vaporised several years ago. But what do you know, I have it, all 18 pages.
Perhaps it promised too much!