Option for custom value on Xbox gift card not showing

Hello Letícia Ayres

Welcome to the Microsoft Community.

I understand that you are having trouble on redeeming gift cards to buy game, and I understand your confusion.

According to your description, gift card options do vary from region to region, and some regions do not have the option to customize the amount. Regarding the purchase of games you mentioned, please don't worry, two 30BRL gift cards recharged to your account can be used to purchase 60BRL games, and the gift cards you purchased are equivalent to the balance of your account after recharging them to your account, so you can rest assured of using them. Just make sure the following areas are set up uniformly:

• Your Microsoft account region.
  
• The region where you purchased the item.
  
• The region of your operating environment (Typically it's your Windows/Xbox system settings.)
  
• The region you are living in.
  

Please feel free to let me know if you have any further updates, thanks. 

Best Regards.

Lee-MSFT | Microsoft Community Support Specialist

Just as others have said, check for any taxes that would go beyond the value of the gift card. When your son goes to the purchase page, does it show the gift card value on the screen?

Unfortunately no, the receipt only shows the lines "retail store open denom.." and then the gift card value. I feel like it might be a special merch card since the supposed $300 gift card they somehow weren't able to issue to me.

Hi Conor! This is possible. You can redeem an Xbox Gift Card, and then use that gift card's value to purchase V-Bucks in-game.

Did you tried to add a low value gift card directly on the xbox?