Get a higher quality router, I'm not sure if by "plugs" you're talking about PowerLine networking (which I don't suggest) or Ethernet networking (which would provide lower latency connections than wireless).
Higher quality routers will come from companies like Linksys and Netgear, I'd say Linksys over Netgear as well. The wireless connection to your house is much different than the wireless networking inside your house, so as long as the modem from the wireless unit on your roof is connected to your router's WAN port, it can be shared.
I have broadband but not through telephone line or cable, because of where I live I can only use a wireless broadband connection. There is a unit on my roof I suppose bit like a hot spot. I am using a belkin wireless router at home which is not great I have noticed you can buy plugs that you put into an electrical point to make the connection to my home computors stronger does this work with hot spot broadband or is there a specific router that would work better than my belkin. I hope this doesnt sound garbled but I am still not tech minded with computors and connections so please excuse me. regards Avril