what you can try is useing a torrent program.
goto this folder: C:\Users\COMPUTERNAME\Documents\My Games\FINAL FANTASY XIV\downloads
you see there 2 folders.
2d2a390f (is from the updater it self)
48eca647 (is from final fantasy)

now goto the directory what gives you problems.
click on the directory: METAINFO

and lick on the latest .torrent file

when download is complete put that what you download in the folder PATCH
start up the game again. you see it want to download your update again. but then it shoots to 100% and start updating it.

if this also failes check your firewall if its not blocking it. (or your ISP(Internet Service Provider) blocking torrents)