You would need to contact PCS, the card is upgradeable, and a simple straight swap, heatsink is identical. If you struggle to get any joy in the UK, then the Clevo 'kit' can be obtained from over the pond: RJTech. But it ain't cheap, esp adding import tax and shipping etc.
Pcs don't do graphics card updates for laptops unfortunately, you'd have to find a third party source and get a clevo card as they're chassis dependent.