After Purchasing the CS 777 in MSFS Markedplace

Welcome to the forums.

This would be the place to try:
https://support.xbox.com/en-GB/help/subscriptions-billing/buy-games-apps/refund-orders

I realised after I posted the link that this was for the UK… I am sure there is a similar xbox link for your country, if this link doesn’t work… or search the web for “xbox refund”