I have a water leak nearside boot by CD multi changer. The water looks as though it is coming through the boot seam but i can see no hole even with the bumper removed. any suggestions as everything is getting damp. it is not the rear washer pipe getting disconnected

Could it be coming in via the rear light cluster?

Does your car have a sunroof? the rear drains for the sunroof exist in this area.

Are you sure you have a leak and it is not just the tailgate opening letting water in due to bad design. That is the area that gets wet due to this issue. I am not sure if you have hatchback or estate so maybe not the same issue. Check out this recent thread discussing various leaks.

http://briskoda.net/octavia-i/what-can-i-use-seal-my-bodywork-leak/136842/

Hatch or estate? I had a similar leak fixed under warranty on my estate, I don't think the dealer actually located the leak but they covered every possible source with sealant and then it stopped. Their first thought was the aerial if I remember correctly but it wasn't that.