I just want to add some tech stuff to this thread so please dont think im trying to baffle you etc I genuinely want to help.
When it comes to broadband its not as straight forward to get things done as there are 2 companies running the show
1. Your ISP they are billing you effectively for all the content you download
2. BT Wholesale - Responsible for the broadband side of your phone line they are paid out of the monthly charge you pay your ISP.
3. BT Retail - These are the guys you pay your calls and line rental too.
Cable is slightly different as you are not connected via a phone line at all but over the same cable that the TV works on.
Both technologies work by the modem/router syncing to the device either in the exchange for ADSL or in the street cabs for cable (TW or NTL).
There are many causes of problems either from the ISP or BT.
ADSL
There are 2 things you are looking for on your line these can be found in your router or device stats for USB devices
Attentuation - The higher this is the further from the exchange you are and as such the lower your maximum speed can be
SNR (Noise) - This figure needs to be as high as possible if it drops below 4dB your line will probably lose sync and drop your net connection.
Cable similar issues if the green light relating to sync goes out and then flashes then it has lost sync to the modem in the street.
If your line is unstable and you keep losing sync especially if it rains or when the street lights come on in the evenings then moving ISP will get you NOWHERE its part of the characteristics of your line and moving ISPs will change nothing.
There are many processes for fault finding you can do
1. Unplug every phone in the house and try the ADSL device on its own see if it improves
2. Try new filters - theyre not all the same
3. Buy a filtered face plate for the wall socket
4. Get rid of the USB modem these are crap and lose sync all the time the Belkin 7633 is a good router under £80 and will hold sync on noisy lines extremely well.
Cable users are pretty much in the hands of the cable co as there isnt a huge run to an exchange if there is constant lose of sync then it needs logging as a fault (easier said than done).
For more help and advice go to
www.dslguide.org click message boards and find the board for your ISP and ask in there, failing that pop into the Bulldog forum, i'm in there (Rich44 there too) and i'll try to help as much as I can).