Belkin N1 Vision and N1 adapter 2.5MB/s Blunder

Hi , im after buying an N1 vision and a N1 USB adapter to improve wireless and wired access to my NAS. Two hundred euros later im only getting 2.3-2.5MB/s transfer rate

So i tried eliminating all the possibilitys for a start i rechecked the NAS throughput rate 12MB up and 25MB down over ethernet no problems there . I plugged out the NAS and set up a share using a shuttle K45 , Which gave the same transfer rate .

A bit confused i called tech support who told me to update the firmware [No changes] , Change the channels [No changes], Move the router around to eliminate interference [No changes even in the middle of the back garden] and finally to piss off [Their's nothing else we can do]

Ive tried installing different operating systems , Different protocals (FTP) but i keep getting the exact same thing my connection status says im connected at 270Mb/s 34MB/s but in reality i only get 1/10 of that bearly any better than when i started with my oem router and wifi .

Can anyone tell me what on earth could be causing transfers on my local intranet to be so horribly slow ?