Xbox live discount 12 month membership not working

Hi, did you read this? How to join Xbox Live Family Pack.

I also read this in that thread in regards to discounts.

Gold Family Pack discounts and membership extensions

If you currently have an Xbox LIVE Gold Membership, you will get a discount on your Gold Family Pack membership based on how many months remain on your existing Gold Membership.

The discount varies by region, and is calculated by first taking the price of an Xbox LIVE Gold 12-month membership divided by 12 months (Gold monthly rate). The Gold Family Pack discount that you receive is the Gold monthly rate, multiplied by the number of
months left on your existing Gold membership (rounded up to the next full month), then subtracted from your purchase price.



Note Your Gold Family Pack membership starts on date of your purchase. Your credit card is charged immediately, after any discounts are applied.

Hey there! Your question is explained on the FAQ page:
http://support.xbox.com/en-US/billing-and-subscriptions/account-management/how-to-join-family-pack

"

Gold Family Pack discounts and membership extensions

If you currently have an Xbox LIVE Gold Membership, you will get a discount on your Gold Family Pack membership based on how many months remain on your existing Gold Membership.

The discount varies by region, and is calculated by first taking the price of an Xbox LIVE Gold 12-month membership divided by 12 months (Gold monthly rate). The Gold Family Pack discount that you receive is the Gold monthly rate, multiplied by the number
of months left on your existing Gold membership (rounded up to the next full month), then subtracted from your purchase price.

Note Your Gold Family Pack membership starts on date of your purchase. Your credit card is charged immediately, after any discounts are applied.

Do I get a discount when I add existing Xbox Gold members to my Family Pack?

Yes. When an existing Xbox LIVE Gold member is added to a Family Pack, remaining membership time is added to the Family Pack membership. For every two months remaining on their current Gold membership, the entire family receives an extra month of Xbox LIVE
Gold. For example, if your child has six months remaining on his or her existing Xbox LIVE Gold membership, when you add him or her to your Family Pack, your Family Pack membership is extended by three months."

I watched the video and tried to redeem the gift card that way and it will work but what I would like to do considering Xbox Live for 12 months is on sale right now is use this gift card for that but when I go to the Microsoft store and I click on deals
and redeem a code for the 12-month membership at the discounted price at tells me that their code is not found, although it does work the other way which is the 6-month option but I'm aiming for the 12-month

12 MONTH XBOX LIVE GOLD MEMBERSHIP

£26.99

www.electronicfirst.com/.../12-month-gold-membership-subscription

Same here, offers 33% discount but when I go on it charges me the full price