Just initiate a chargeback/transaction dispute on your form of payment, especially if you paid Microsoft directly. Chargebacks actually cost the subject company money and negatively influence their credit to the maximum extent that you as a consumer can.
Keep in mind that most companies, including Valve for you Steam buyers, don’t take kindly to this action. You can expect some form of retaliation.
EDIT
Also, if you feel mislead, or the product is not what you paid for, if you’re in the United States, you can file fraud complaints with your States’ Attorney General’s office, and/or the Federal Trade Commission at ftc.gov.