You have read this status post. What will you do next, Brave Adventure? A.) Surf the web store and cry due to lack of money. B.) Look for a commissioner and then cry due to lack of money C.) Cry due to lack of money to check lack of money. D) All of the above.
So a glitch in Steam allows people to use other peoples accounts to purchase stuff. Protections like Steam Guard have no effect on these cases. Check your account (and card info) in case of abuse (this is serious).