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Our line appears OK now - although I have just given the service provider the benefit of my opinion on their crap service. Not sure it helped that when I called them I had to talk to "Brian". Unfortunately "Brian" sounded like Achmed the Goatherd in Mumbai. I had to get him to repeat everything 4 times. He tried telling me it was a fault with our equipment "Oh no it isn't because if it was, I wouldn't have connected to some poor random woman three miles away". We had a frank exchange of views on that.
Brian "Find the main junction box".
<<BM climbs over numerous piles of papers, moves various boxes out of the way, nearly poops herself at enormous spider in the corner>> "Yep, got the main box"
Brian "Does it have line running through it"
BM "You tell me, you just tested the bloody thing".
Brian "No I mean straight line through middle of box"
BM "Yeah sort of"
Brian "Does it have screws"
BM "Yeah 2"
Brian "well now unscrew front panel".
BM "You mean I need a bloody screwdriver................" Thinks "you effing muppet, of course I always have one handy in my pocket".