Over the last few months, that deteriorated, and when I checked it last weekend, I could rarely get better than 1.4Mbps.
So I logged a problem with the HelpDesk. On Monday, a linesman let me know there had been some cross-circuit problems, but that still didn't fix things.
Yesterday he came by home - and found that one of the two copper wires just outside my house had pretty much disintegrated. There was a 10mm gap in the copper. My ADSL was coming in on one wire only...
New wire to the house, and my speeds are back to 12-14Mbps. Happy with WxC and their HelpDesk's assistance. Amazed at what I had been putting up with while that wire was corroding away to nothingness!