Claiming refund for incompatible redeem code

I'm sorry, since you bought a code from a third party, it is not refundable

If you hadn't used it you would still need to ask the retailer for a refund. Microsoft can only refund purchases made on their store

You can play the game through the cloud with an Xbox Ultimate subscription on Xbox One

• Buying or redeeming game content or codes from illegitimate third-party websites
  
• Claiming that successfully redeemed codes didn’t work to gain additional content or funds from Xbox Support
  
• Abusing the Microsoft refund policy, or circumventing the refund policy by applying for “chargebacks” with your bank or financial institution
  
• Using system glitches or loopholes in the store for financial gain
  

i followed the link and followed the steps, but it does not give me an option to claim the refund. i know he has not redeemed the code because it would not let him.

it just took me to a page of the things i have recently bought, but doesn't give me any options to refund the dlc.

Unfortunately for you, since you used a VPN to redeem the code you would not get a refund since they don't refund codes that have been redeemed. You could have gotten the refund if you had not done the work around to redeem the code.

So codes are refundable??

If the code was already redeemed then no it wouldn't be refundable.