SatNav Head unit Display

[Grommit]

Hi all,
I've got a problem with the display screen (16:9)for the SatNav etc.
It is constantly scrolling diagonally, it looks a bit like an old TV when you needed to adjust the vertical or horizontal hold.
Is this repairable? If so does anyone have contact details for a repairer?
If not is it worth getting a second hand head unit off EBay?
I see there are several replacement units on sale, which is the best one?
Do they still give you access to the original menu functions i.e. Webasto heater control, TV, telephone etc?

Many thanks 

[Greydog]

Is it the head unit? I thought the head unit is only a display for the signal sent from the TV/Video unit by the Nav, Radio etc.
I could be wrong of course but I think you need some diagnostics done.

[X5Sport]

More likely to be the video module in the boot.

Richard

[Grommit]

Thanks guys,

it would appear to be something loose in the head unit. Took it out, had a look, reseated everything, put it back and it's working again, don't know how long for though