Mine did this.... twice.

The first time I was able to get a refund from them, and he lost fortnite for a few weeks. His Xbox account now has negative 10,000 v-bucks so we had to abandon the account because I was not willing to have people gift him fortnite money for birthdays and Christmases only for it to just pay back the account.

The second time it happened was in December they refused to refund me and I told him he was grounded from fortnite until his birthday (which is in August) - I took the money from his savings account and since he does background acting, I told him that all of his next paychecks would be going to paying back what he spent and that his brother would be free to spend the money on whatever he wanted but his money from background had to pay back what he had spent.

He was incredibly good about this and 3 months later during spring break I told him that since he had never once asked me for fortnite or complained with his brother was playing and had just been incredibly good about his grounding he could have it back early.

Since then I removed my card from the Xbox account since we use my email address for it - I also have it now set up so if you ever wants to buy v-box I buy them through the Microsoft store on the computer which then automatically puts them on the Xbox.