Thank you for contacting Steam Support.
Our system indicates that the account has been permanently banned by the Valve Anti-Cheat system (VAC) - Steam Support is unable to lift the ban.
We will not disclose the cheats which were detected, nor will we provide the date and time the infraction took place. VAC has confirmed that the ban on the account was applied legitimately.
This ban applies to a Steam account (regardless of who was using the account at the time the infraction occurred) and any VAC protected games registered under the account at the time of the ban. The use and security of the Steam account is your responsibility.
This ban does not affect third party games that are tied to this account unless otherwise noted. To see which games your VAC ban affects, please launch Steam and go to File > Settings > Account tab > select “Click here for details” under VAC Status.
The account may still be used to play single-player games and to connect to non-secure game servers or LAN games in the games the account has been VAC banned from. Please change your filter settings in the server browser list to show servers which are not VAC-secured (from the Steam main menu go to the "View" option, select "Servers", then "Change Filters", and select "Not secure" in the Anti-Cheat drop-down).
We cannot move game subscriptions from accounts which have been banned by VAC.
If you choose to purchase a new copy of the VAC banned game(s), please create a new Steam account to register the games on. Remove all cheats from your system before you install (if you do not know where the cheats were installed, you may want to consider reformatting the machine and starting over with a new installation of your operating system).
For more information on Valve's policies, please see the Steam Subscriber Agreement and the Rules of Steam Online Conduct:
Steam Subscriber Agreement
What is Steam
Rules of Steam Online Conduct
Steam Online Conduct