In building solutions are normally the domain of the business teams but most networks have been trailling pico cells that act as mobile transmitters but work of your broadband line (I used to work for Orange and ran a technical trial). Not sure whether o2 do it but that is the official way to get the signal at home. Never heard about the repeaters but I would guess tackling the network first would be the answer.
Here's one of the old press releases you can read up on so you can show 02 you know what you are talking about, there is plenty more about it on the internet.
http://www.theregister.co.uk/2007/10...nge_picocells/
Cheers.