September 2014
Over the weekend, we discovered a Hockey Ultimate Team pack exploit on the NHL 15 Store. Until we resolve this issue, the majority of purchasable packs will be unavailable. Currently, the only available pack for purchase is the Gold Premium Jumbo pack.
We're sorry for the inconvenience and thanks for your patience while the NHL team works on a permanent fix. Please stay tuned for updates.
Source: http://help.ea.com/en/article/hockey-ultimate-team-packs-removed-from-nhl-15-store/
October 2014
Thanks to help from the community we were able to track down the exploit and deploy a fix and as of now, the HUT store is fully back online.
Our team is also working on identifying those who took advantage of the exploit and depending on the severity of the abuse, we will be taking action against specific accounts.