HORRIBLE connection for a week from sky!?

[Southpaw]

I think that you need to investigate why Steam is slow rather than questioning the capabilities of your ISP, although I do tend to agree with your opinion of them.
Have a read of the Steam help site below and see how to change the "content server" to see if there is a faster one in a nearby country, after all, you can only receive the data at the speed it is being sent down the line to you;
https://support.steampowered.com/kb_arti...-WPDF-3220
Edit: if you are in the UK then sometimes the Irish or French sites are faster.
Using a WiFi connection is never going to be as fast or reliable as connecting with an Ethernet cable, but it can be improved upon usually, so have a read of this;
http://aspenitcouk.wordpress.com/2013/05...s-network/
That`s about all I can suggest, Sky hire BT lines to rent on, as do most other broadband providers, so changing providers usually does not improve speeds as they are all using the same line plant.
Best of luck with it anyway, regards, Bob.