Just to clarify a few points.
Dave B’s right, there’s no statutory requirement for Strata Managers (SM) to send out quarterly notices of contributions, but there IS for Owners Corporations (O/C), and that function is customarily (if not always) delegated to the SM in their Agency Agreement with the O/C. Why would you engage a SM otherwise?
The NSW Strata Schemes Management Act states at Sect 78 that the manner of an Owners Corporation levying contributions to its Administrative and Sinking Funds will be by it “serving on each Owner a written notice of the contribution payable”, and further that these notices will be by way of “regular periodic contributions”.
The Agenda of each Annual General Meeting (AGM) must include a Motion to determine how much money the Owners Corporation needs to collect (via levies) in order to properly manage and maintain its Strata Scheme, and at that same Meeting must also determine the amount of each Owners contributions in accordance with Sect 78, and at what regular periods notices of those contributions (invoices) will be issued.
So have a look at the Minutes of the last AGM and see what’s been recorded there re. the above, and re. any un-financial Owners being shown as in attendance and entitled to vote; because as Dave B has advised, they can’t.
Now that those dreaded legal bits are out of the road, you must have a look at the Agency Agreement that your O/C has (in fact must have) with its inept Strata Manager (SM), and look for the section where the functions that your O/C has delegated to the SM include the issuing notices of contributions; I’ve never come across a instance where that’s not the case! Also look for the SM’s “debt collection procedures” as those customarily include reminder letters (that sometimes attract a fee), recognising that your O/C can decide whether or not the charge that statutory interest rate (10%) on overdue contributions beyond 30 days.
When you sorted all that, you really need to sort-out your inept Strata Manager, firstly by sourcing a new and better one, and then by your O/C moving to terminate that Agency Agreement – after first checking the conditions attached to that such as providing three (3) months written notice of termination in advance of the expiry date shown.