Broadband (ADSL) connection keeps failing after rain

[buildersmate]

Every time it rains or humid conditions exist I keep losing my ADSL line. It connects, then fails after a few seconds, a typically lasts for a few hours. I appreciate this is probably something to do with a reduced impedance down the local loop back to the exchange. Is there anything I can do about it? Who do I complain to - my Broadband provider or BT?

[Catso]

It shouldn't do this, sounds like a dodgy connection somewhere. Initially, report it to your ISP, they'll pass it on to BT.

Problem is, being intermittent, it's going to be a b****r to prove, or fix!