Unable to Update Adobe Acrobat 8 to 8.1.0

Hi all

I have recently installed and activated Adobe Acrobat 8 Standard. I wish to update it to the latest update (I believe is 8.3.1). I tried to update by going to Help>Check for Updates however it stated "No Updates Available - Unable to check for updates at this time". I understand that I need to update these in stages, is there a download location for 8.1.0 to start?

I am aware of the FTP site link ftp://ftp.adobe.com/pub/adobe/acrobat/win/8.x/8.1/misc/ , however I am unsure which file to download.

Any help would be appreciated

Thank you in advance

Jamie