pond liner

I have has a problem over the summer with plenty of dead fish. we have had
everything checked out even had pond doctors drink my pond water and profess
that they would stick their fish in that, when pressed of course they didn't
in fact put their fish in my water (so to speak) any way we had to eliminate
everything one by one right down to just the pond liner and the water
(difficult to test without the water) any way our fish still kept dying. so
we checked out just the water by putting fish in just a plastic bucket. low
and behold they live. SO WE HAVE A DODGY POND LINER the suppliers recon
there is nout wrong with it but as soon as you put a fish near it the go all
fins up.

Question has anyone else had pond liner problems?