Sky on Demand repeated disconnection problems since switching to Plusnet

[#1]

I switched from EE to Plusnet within the last month and ever since I have, my Sky On Demand service keeps disconnecting. I have to reset the connection at least once a day.  Sky were completely unhelpful and suggested I opened a new port.  Plusnet sent me a new router which has made no difference and when I asked them if they could open a new port they advised that wasnt their area of expertise.  Im not a techy person and Im very frustrated with the whole thing.  Last weekend I spent 2 hrs on the phone with both Plusnet and Sky being batted between the 2.  Nobody cares and Im stuck in a contract with Plusnet now which i don't want because the wifi service isnt working correctly.
I'm unable to connect with an ethernet cable as too far away.  I dont feel it's a plusnet problem but as Sky won't help, i wondered if anybody else in the forum has had this problem?

[#2]

I have mine wired with home plugs as I don't have a wifi HD box.
Mark

[#3]

Does your Sky box have built in WiFi or are you using the Sky adapter?
Have you tried updating the firmware on your Sky box?

[#4]

I use mine wired as I dont believe in wifi for hd streaming, however my parents box uses the sky wifi adapter and works fine, with the standard plusnet rourer.
What happens when it disconnects? Does the box reconnect automatically or do you need to do anything to reconnect? Have you looked at the sky box network setting just after it disconnects and if so what does it say.
I presume you are using a tg582n.... when the sky box disconnects can you access internet on other wireless devices?