Here is a message I've recently got from Marriott:

Dear Valued Member,

On behalf of everyone at Marriott Rewards®, thank you for making us your choice. Recently you registered for an Air China Phoenix Miles promotion. We regret to inform you that due to a vendor system error, the promotion was mistakenly publicized after it had ended. The promotion is no longer available.

We sincerely apologize for this mistake and are crediting your Marriott Rewards account with 500 miles for any inconvenience. Please know we are taking every step to make sure this doesn’t occur again.

Sincerely,

The Marriott Rewards Team