iTunes giftcard giving me less than its actual amount

Hello, i’m a person that lives in norway, and i’m having issues with my giftcard redeeming. I bought myself a $15 gift card, but it only gave me $8 for a weird reason. Here’s the proof:

“150 kr. ($15) Has been implemented to your apple ID. You now have 83 kr. ($8.30) in total.”

I’m not sure why this happened, but if it was because some of my payments was on wait, then it didn’t give me my reward that I was supposed to get. If there is anyone that can help me with this, please do. Because I really want my last $7 back.