Originally Posted by ChocolateFactory

We were a group of 8 people who went all in on this promotion (received 720k Avios).
Only 3 of us got the email.

Account 1 (old account): All Avios spent => no email
Account 2 (old account): All Avios spent => no email
Account 3 (new account): Spent 89,050 Avios, bought some more Avios through Groupon, then refunded some tickets, now many thousand Avios left to spend => no email
Account 4 (new account): Few thousand Avios left => email received
Account 5 (old account): All Avios spent => no email
Account 6 (new account): Spent 89,050 Avios, bought some more Avios through Groupon, then refunded some tickets, now many thousand Avios left to spend => no email
Account 7 (new account): Few thousand Avios left => email received
Account 8 (new account): Few thousand Avios left => email received

This is just a very, very wild guess, but one conclusion from this could be that they can correctly track redemptions, but unable to connect refunds to this.
So if you have absolutely no idea what to redeem your Avios for, I would at least try to redeem for something on IB/BA metal and than cancel and ask for a refund (not sure whether it's better to request the refund before or after Dec 1).