The most likely thing is they have blocked your ip, easy to check switch your router to modem mode and try to access it with a wired connection, if it works it's because your ip has been blocked and only their it guy can unblock it
The current set up won't work as the 360 only has a hdmi port, there is a mini scart port but it's disabled, there's no simple solution, you could try an hdmi spliter with an hdmi to scart converter but this tends to be unreliable, also the 360 remot...
Phone up at 8am when the lines first open dial 150 or 0345-454-1111 then options 1,1,4,4make sure you inform them it's because of the price increase, you should receive a confirmation email within a couple of hours