Cant upgrade to 8.1 on XPS18

Hello,

Ive got a Dell XPS 18, with windows 8 on it.  Ive tried to download the windows 8.1 update from the windows store but it wont download fully.  It randomally resets at various points during the download and starts the process again.

I've tried,

1. using a USB to ethernet cable into my router to rule out my wifi.
2. Leaving it on all night trying to download
3. uninstalling all antivirus software incase that was causing an issue

I'm looking for any advice or suggestion on what I could try next.

Thanks for you help