>> my downstream is between 3.5 and 5.5/upstream around 360.
Im presuming you mean the speeds you are getting?
Its nothing to do with your attenuation Im afraid... on those stats youre well capable of more than 8Mb on adsl2+
Upstream seems about correct..
Downstream.. that depends on contention and how many others are using their connection at the same time.
When I first got maxed I saw 7Mb offpeak.. and about 5Mb during peak time... those speeds gradually reduced until a couple of months ago, they were nearer 2Mb at peak.
Bt recently upgraded my exchange and now Im getting about 7Mb off peak 5-6Mb peak.
Have a read of this
http://www.kitz.co.uk/adsl/acceptablespeeds.htmand also this
http://www.kitz.co.uk/adsl/slowspeeds.htmunder the bit about exchange congestion
Theres also a link in there to an exchange checker where you can see if your exchange has any reported problems and any fix dates.