Looks like now they want to clear out the S21 +. Not sure about the loyalty vouchers and newsletter.
Unobtainable as at 21/12/2021 10am - refer to comments, no successful orders using the trade-in discount promotion of $500 reported yet.
Available again at 2pm - refer to comments, Asurion confirmed trade-in services was undergoing maintenance but are back online.
Thanks OP
Ended up getting the S21+ 5G 256GB in violet
$499 after $100 loyalty voucher (issued before 16 December when they stopped issuing them) and $550 trade in of perfectly working S9+.
Couldnt get the $50 newsletter voucher to work. But pretty happy at that price.