My ADSL2 sync speed has dropped recently from 8mb/s to 4mb/s, and upload speed has dropped from around 1mb/s to 0.3mb/s. There are loads of signal errors on my router, even when plugged into the test socket. And my phone line doesn't give me a dial tone when I plug the phone into it (also test socket). On top of that, when I try ringing the line using my mobile, it rings weirdly, and when I answer it, I just get an intermittent buzzing noise, nothing else.
It's a BT line, and I'm on O2 broadband connected at the Kingsland Green exchange. What is going on?