No intenet: what are my options? (question #3088907)

[#1]

An intermittent fault usually results in lower speeds and a higher SNR (that's actually the way DLM is designed to work).
If it stays stable this should reduce on it's own, giving you higher speeds again.
I'd keep an eye on it over the next couple of days and if it drops again get the engineer booked.

[#2]

Well, it went down again with PPP failure  sometime during the day, after being up all week.
I've answered the update on my question with the times I'm available for an engineer visit.

[#3]

Quote from: mjhoward

I've answered the update on my question with the times I'm available for an engineer visit.

Which apparently sat there un-viewed for nearly 48 hours, until I called up to check. 

[#4]

Well, after deciding at the last possible moment that they didn't want to send me an engineer a couple of weeks ago, but instead do more tests...  BT now want to send an engineer again.
Unfortunately, it's all a bit too late. After having no internet connection for most of November and December, I've signed up for telephone and internet with cable. I'll be cancelling my BT phone line and my plusnet account in the next few days.