Hi all - a friend of mine at work has a GT (wanted a GTI but company car allowance couldn't stretch

) and has a very annoying problem regarding a thumping noise and vibration coming from the rear wheels at all times but it is most noticable around 30mph.
There is some slight feathering on the inside tread but hardly noticeable.
He had the wheels switched with those on the front and the noise/vibration moved with them to the front.
He's taken it to VW 3 times in the last 9 months for laser alignment and they say that they can't find anything wrong.
He's had it checked at a local Humphries who helpfully stated that as the tyres wear the more feathered they will become and its common....personally i've done the same amount of miles on my tyres and i'm not getting any thumping/vibrating so i think the Humphries guy has no idea what the problem was and picked a default answer.
Does this sound familiar to anyone?
As its a company car they should change the tyres FOC but as VW say that all the alignment is perfect and they can't see an issue they are refusing to do so.
Any ideas?
Iain