If u you log in to your account, go to make an award reservation as normal then for points required it will show "0" points instead of the regular points, then when you click through the rate description will show the free night promotion.

For the "0" points to show you have to meet the original terms (I think free nights have to be used before 30th December?) if your trying to book after this date it will not work.

Not an easy system they have set up...