I live in the Kensal Rise area of London, where we experienced a tornado 2 weeks ago. Since then, my internet access has been working sporadically (and most recently, not at all), I'm receiving some emails but not all and can't send any at all. My broadband supplier (Waitrose) says everything appears fine their end. We've changed the microfilter and been through the preference settings so many times... but to no avail. I'm tearing my hair out - any ideas what's wrong?

I don't think this has anything to do with your Mac. This is more likely to be due to the main telephone and broadband circuit in your area.

You should contact BT and ask if they can do a test to see if there is a problem. Are you able to ask neighbours if they have problems with their broadband? This may throw some light on the situation. Hope this helps.

Yep just to echo what mac genius said. The provider, in this case Waitrose really are at the mercy as you are of BT. Problems like this can drag on forever in some cases, not so long ago one of our neighbours had a faulty power supply in their home which was causing interference to our Broadband...took BT 3 months to find the problem and fix it