Sorry, I can't help you with your problem but I can commiserate as I have exactly the same problem. Just over 2 weeks ago my broadband speed with BT was excellent but since then it has been dire and has the same profile as your problem. After several calls and several tests with to BT over the last 2 weeks they seem to have no answer to the problem except that they think it's at the exchange. If that is the problem then why don't they get an engineer to sort it. My area code is 01633.