Update.
Got rid of that POS Erisin android head unit. When I visitng Car Audio Security, the fella there recommended a Kenwood headunit. Fitted that today and the sound quality is amazingly better. This is, using a MOST Decoder, though when this was used with the erisin unit I was getting all this static noise etc. Nothing so far with this new unit.
Another expensive lesson learnt (Common phrase on this forum)
My Advise to any W211 owners. Avoid the cheap stuff. Stick with the good brands.
Thanks