Unable to purchase Minecoins

Hi, we are unable to purchase minecoins from my daughters account, she received a gift card, she’s got money on her Microsoft account but the store on Minecraft won’t let her buy the coins. She receives the following message:

Something went wrong 

Sorry, we were unable to complete your purchase.

Maybe check your internet connection?

Yet our internet connection is perfectly fine.

Does anyone have a solution for this? She’s looking forward to all the cute texture packs for months poor thing.

Thank you so much for your help.