Issues redeeming minecraft minecoins gift card on android tablet - I did not receive a 25...

My son received a Minecraft minecoins gift card for his birthday, which was purchased at Walmart. After finally receiving the receipt with the activation code, I found that it was not a 25 digit code but a 14 digit code. There is no way for me to redeem with a 14 digit code. Has anyone had success solving this issue? I tried to contact Microsoft support to get a new code as I saw suggested somewhere, but they referred me to the game developer and then attempted (unsuccessfully) to transfer me there, resulting in the call abruptly ending. The card specifically states android among the many systems listed as an option for redemption. Any suggestions are appreciated.

:)