Lost my broadband connection!

[#1]

My BB has been working great for over 12 months on Plusnet but while surfing Ebay recently things started to slow down and finally ground to a halt.
I have checked that I am synced to BT ok, my connection stats show I seem to be connecting to Plusnet ok.  My wireless link to my router shows nornal,  but I still cannot surf as I keep getting 'page not available' messages after a time out period.
I can surf ok using dial up but very slowly (this is quite nornal for my land-line)  using my old dial-up account.  I have run A/V scan and also done a system restore to time when BB was work ok.  I am running Wins pro and I/E.
I have looked at Plusnet help pages but because of my very slow dil-up connection each page takes 5 mins or more to load so are no help is this case.
What do I check next.  Any help would be much appreciated.
Paulo

[#2]

Can you connect to other websites except ebay?
Does it happen all the times during the day, or only when the Internet gets busy?
When it happens can you connect to www.google.co.uk (delete cached pages first)?
If not, can you connect to 66.102.9.147 even though you cannot connect to www.google.co.uk?

[#3]

Hi Mick,    Cannot connect to any site.    Plusnet have now taken up this problem and imply that there is a possible fault at there end.
Paul.

[#4]

I have a 2WIRE 1800HG which has the same chipset as the early 2700HG and can confirm that it holds the line better than my DG834v1 and DG832GT.  However, with the nights drawing in I have noticed a couple of retrains over the last 5 days.