Powerline Ethernet Adapters - can they be used like repeaters?

Powerline Ethernet Adapters - can they be used like repeaters?

I'm helping a colleague with their home network. They want to be able to use a couple of wireless laptops anywhere in the house. The wireless router from BT covers the study and the lounge, and a wireless access point plugged into a powerline ethernet adapter covers the kitchen and another room. However, the wireless is only barely available either upstairs or in their games room.