Internet speed slowing or dropping

[MichaelZZ]

Desktop PC. Windows Vista Home Premium 64 bit.
I have had my wired broadband with O2 for 3 years now and have generally been very happy with it. The Customer Service people have, on the rare occasions that I've needed them, been excellent.
My download speed has typically been around 4Mb/s. Recently, however, I've had problems with my download speed dropping to less than 1Mb/s after I've been using it for an hour or so. Sometimes it corrects itself if I reset my router, other times that makes no difference. If I switch everything off and restart from scratch after a few minutes, all is then well for another hour or so.
I spoke to a Customer Service chap and he said he would do some tweaking to improve my speed. The minor improvement he made didn't last. When I called back he told me to change my ADSL filters - which I had already done - and finally said that he couldn't help anymore as my router was plugged into an extension socket rather than the BT master socket. He suggested that I should fit a wireless card into my PC and relocate my modem / router near to the BT master socket. He did not seem to understand that I have had the same set up with the extension lead since Day 1 of my broadband and something somewhere has changed or deteriorated. I have no need or desire to go wireless.
I have established that the O2 tariff that I'm on is not subject to "Traffic Management" and in any case my total monthly usage is only around 10GB.
Could it be that my router needs replacing? (I am using the one supplied by O2 when I signed up 3 years ago?)
Any thoughts would be gratefully received. Thanks in advance.

[daffy654]

It is definitely worth asking them to replace the router/BT Home Hub after 3 years. If you threaten to take your business elsewhere they are usually happy to help you out ;)