Help on Highend Demo Upload

Hello, I recently bought the Highend theme via MOJO marketplace and I am with fasthosts.co.uk.

Have been trying to upload the demo content and tried both through the Dashboard (Demo Upload) as well as through WordPress manual upload. But while the former process seems to be taking forever, the latter ends up giving me a 504 gateway timeout after a short while.

Just wondering if you can help me with this please?

Thanks