I posted about this issue a couple of years ago - every year the problem re-occurs and never seem to be able to resolve it, so I'm throwing it out to you good people again in the hope that someone can help me track down the cause of the fault. Here's my original post from 2 years ago:
"A few weeks ago I was experiencing intermittent noise on my phone line which was causing intermittent Broadband line drops and consequent severe speed degradation (download speed eventually dropped to 15 kBp/s !
I noticed that the problem was worse when the weather was warm/very warm - however as the weather cooled down the noise diminished and the line speed improved. A BT engineer came out to look into the fault but due to the intermittent nature of the fault he couldn't find a problem - by then the weather was on the cool-down anyhow so the fault was easing off.
Naturally for test purposes I disconnected all my equipment, changed filters, used only the master socket, etc all to no avail. Also tried a different router.
Since then the weather has been relatively cool but over the past few days has started to warm up again and yes, you guessed it, the fault is starting to re-appear. Only two line drops so far (one 3 days ago, one a few minutes ago) but intermittent noise on the phone line (although the automated BT test declares that the line is okay - I must be using it at the wrong moment!). Broadband download speed has dropped back to 200 kBp/s (used to be over double that).
So what can I do?
The fault is obviously heat (or sunlight?) related, but how do I convince BT to get the problem sorted?"
Note: As of this year I haven't involved BT seeing as they couldn't resolve the issue last time (and the time before that (when looking into the same fault) they managed to disconnect my phone line and Broadband COMPLETELY for nearly two weeks before they were able to fix it, so I'm treading VERY carefully this time!).
Thanks