Don't be fobbed off: your rights returning goods

A friend of mine recently got involved in a tussle with a retailer who'd sold her a laptop. The thing stopped worked within a couple of months of her getting it home - so she took it back to the shop and asked them to sort it out.

The retailer insisted she take it up directly with the manufacturer. And, of course, the manufacturer pointed her straight towards the retailer. So who was correct, and who are you supposed to deal with?...