ACT strata law is very similar to NSW’s so I’m taking a punt here; generally speaking, unless they have delegated authority to do so, the strata manager should only be making payments that are authorised by the committee or owners corp as a whole.
So somebody is telling porkies; either the strata manager or a committee member who gave her the go-ahead and is now feeling the heat. Approval for expenditure over the phone should be done in emergencies only. Forgetting to tell the committee that you have lined up a contractor is not an emergency.