Are you connecting wirelessly, or via a cable between your computer and the router? If wirelessly, you first need to establish where the bottleneck is - in your wireless or in the connection itself. Connect your laptop or PC with a cable and see if it helps. If it does, the wireless is the problem. If not, you've excluded that as a possibility.
If the wireless is the problem, your surround sound could be interfering, anything electrical theoretically can, but it's more likely to be something that also uses wireless technology, like a cordless phone. Alternatively, wireless routers can use several 'channels' to broadcast the network, and if your neighbour's router is using the same channel as yours, that could interfere - change the channel (your manual will tell you how) and again, see if it helps. Final possibilities are someone else using your connection (I assume when you get your 0.2Mbps you're the only person in the house using it), so make sure the connection is properly secured and password protected, a fault in the router, or a settings conflict of some sort - the latter would be a bugger to track down, so try all the other stuff first.
If you're not on wireless, or you are but things don't improve when you test with a cable, you need to establish if the problem is with your equipment or settings, or if it's a connection problem Talktalk's end. You can't do anything about the latter, they'd have to fix it. The former - well, router could be faulty, do you have a spare to test with? Also, even if you're on a cable, if the router is wireless capable and the wireless is on, make sure it's secured or someone could be piggybacking onto it.