If you are having difficulty purchasing the expansion from the in game links, try searching the Xbox One store for "rise of iron". There will be two listings - one will say bundle only. It is the other that can be purchased as standalone RoI. Be sure that you are logged into an account that purchased TTK from the Xbox live marketplace, or an account that redeemed a code for TTK from a physical version. This is a requirement to purchase standalone RoI. Accounts accessing a copy of TTK owned by another account, are not eligible to purchase standalone RoI. If you are logged into an account that has directly purchased TTK, and the listing still shows as "Not Available", your TTK license is not being recognized. Try restoring licenses: https://www.bungie.net/en/Help/Article/12181 If after that the listing is still showing as not available, you will have to contact Microsoft. As owners of the Xbox live marketplace and your Xbox live account, only they can resolve any issues with the store or your account.