Problems with Wireless broadband to existing networked house

Hi

I am having abit of a drama with this new spark wireless broadband. The place where I had allocated for my modem/router to go. Does not pickup great signal. very little I may add.

Is there a WiFi extender / router I could use with the wireless broadband modem from spark to pick up the signal and distribute it throughout the house

Any help would be much appreciated

Cheers

N