I have 15K pending credits and when i go to my statement it says total pending rewards credits ...

Hello ZombieEater189,

After looking at your MyStatement on the MyRewards page, it looks like you may be looking at the Lifetime Microsoft Points Earned: 0. Microsoft Points was the previous Microsoft currency that has since been disabled. I see that your 15,000 Credit event is
currently listed in your MyStatement, and that these Credits are correctly listed under Lifetime Credits earned.

On the MyRewards section of the Rewards site, Scroll down a little bit and you'll see "My Statement". Underneath that, it will most likely be showing you your pending credits. There's a link underneath the Pending Credits heading that says "View statement".
Change the option to Lifetime Credits Earned and you will see a complete history of all credits you've earned in the Rewards program as well as when any of them were deposited.

The deposit you see on the billing site, would be a deposit of around 7,000 credits.

Your lifetime credits earned is the total amount of credits you have earned since joining the program. It includes credits that are still pending as well as any that have already been deposited. If you check the MyRewards section of the site for your statement
it will list the amount of credits you have pending. If the amount of pending credits is smaller than your lifetime credits, then you've already had deposits. Your statement will list when any deposits took place and you can check for those deposits by looking
at your returns at http://commerce.microsoft.com

Lifetime credits is the total amount of credits you have earned since joining the program. That includes all credits that are pending as well as any that have already been deposited. Your statement on the MyRewards section of the rewards site will list when
any deposits took place and you can verify deposits at http://commerce.microsoft.com

For help with the rewards program, it's best to post in the Xbox Rewards Questions support forum.

Keep in mind if it says Lifetime Credits earned, that is a total amount of credits you have earned since joining the program. It includes any credits that are pending as well as any that have already been deposited. So if your pending credits is less than
your lifetime credits, you have had credits deposited in the past. Your statement would list when any deposits took place. You can verify deposits by checking your refunds on
http://commerce.microsoft.com It's not possible to use currency from your Microsoft account balance to purchase gold through Xbox.