How to make a game bought in Malaysia work in UK

Hi - I’m a new newbie. Actually, a rather elderly newbie living in the UK.

We recently visited Malaysia and my 14 year-old son bought a copy of Team Fortress 2 from a major bookstore, thinking it would work on his computer when he got back home. No such luck! The back of the box does say ‘This product is licensed solely for use in Brunei, Cambodia, Indonesia, Malaysia, Philippines, Singapore and Vietnam’, but it was the front of the box on display and no-one noticed the small print until we got back to England.

Steam loads OK, but when the game is loaded and the product key is entered, up comes the message saying Not licensed for use in your region.

I have AnyDVD running, and DVDRegionFree+CSS, but neither overcomes the region blocking.

Also have tried on two different PCs, both running WinXP.

Any suggestions please?