vw bora - poor radio reception

bought a 03 bora a few months back. it had a jvc radio in it with poor reception. kept coming and going.
got a new kenwood fitted professionally but still have same problem.
fitter says radio is working fine that it might be the aeriel lead is faulty somewhere between the dash and mast on roof.
anyone have any experience of changing aeriel lead? (fitter won't go near it!)

The original radio powers up the aerial through the aerial lead. aftermarket radios dont have this feature, you need to purchase a power supply or aerial booster as some people call them.
They are only a few euro in your local motor factors