Update - I have been emailed by broadband support who requested I re-run the speedtester on the ADSL, even though I passed them all the results from the previous test. Undertook the test again with almost identical measurements (300kbps download). I am awaiting their response.

It would appear that they eventually fixed the fault, still not had a call from them, but now getting about 8Mbps at peak periods, They seem to specialise in passing the buck and blaming everything but the cause, this is not the first fault i have had to report to BT but lets hope its the last

martin