Originally Posted by
BrightlyBob
A challenge occurs where you are set a minimum number of nights to acheive in a short space of time to be bumped up, typically 12 nights in 3 months for Gold, 18 nights for Plat. You need to call the Marriott Rewards line to set it up for you.
I was offered the 18-night challenge late October to retain Platinum without calling, am nowhere close to hitting it.