I think you know that nothing new can be added to the agenda once the meeting notice is served (with due notice).
What to do; I think you also know that depends on what is brought up, passed and actioned. As we are all too aware CTTT are not going to automatically invalidate something just because process was not followed.
Just sit back, enjoy the show and hope you get the big levy increase that means you can help others pack .
You could reply to the email with parts of the SSMA which make it clear new items are for the next agenda, not the upcoming AGM. Schedule 2 clauses 35 and 36 covers it, it is simple to read and it is not quantum physics, so if the Chairperson still allows any new motions at the meeting then he/she does so with complete disregard for the SSMA.
I sometimes wonder why strata even has rules given most of them can be so easily ignored with little fear of repercussion.
The idea of adding to the agenda 4 days before the meeting is wrong and there is little can be done to stop it if the EC wants to do it; you can only potentially deal with the after effects if they are genuinely detrimental.