noisey gearbox 02 reg mini one

[lenno]

hi new friends,i am new to the forum stuff but i need technical help about my little brothers noisey gearbox on his 02 reg mini one.
It was registered 02/03/2002 and has now covered 52k.When setting off from a standstill there is a gearbox noise apparent in all gears but louder in 1st,2nd and 3rd as the speeds,wind noise and road noise is low.I have pin pointed it to either input shaft bearing or diff bearings failing.
I have read on the net that these are "midland"gearboxes and are not the most reliable,is this true?
if so,can anybody tell me if my symptoms are common?
Do bmw recognise this as being a build quality fault ?
and is there a recall or warranty bulletin in circulation?
As you can tell i am in" the trade",i am a vauxhall and mitsubishi master tech.I have enquired already to a local bmw dealer and straight away the service advisor said bmw will contribute "a good will gesture"on parts but not labour.Firstly i was suspicous that over the phone to be told this leads me to believe its a known fault.I would rather they paid for it all as parts would be approx £150 and the labour approx £600 and just need the ammunition for when i go into the dealership tommorrow.I am also aware that if its a known build quality fault then the manufacturer has to repair the vehicle under warranty for up to six years old.
sorry for going on people but i ve finished my rant now,please can anybody help?
Andy