A couple of weeks ago I bought two tubs of emulsion from Focus at £13 each, buy one get one free. The offer is still on and, since my parents wanted some paint as well, I said I'd get a couple for them. As it turned out, we didn't need one of our tubs. So in I go, put the unwanted one on the till plus the two for my parents (£16 each). What happened was I got a £6.50 refund on the one I returned, which was taken off the new ones - so they ended up at £9.50, buy one get one free. I had expected to give back the unused one for nothing and pay the full price for the new ones. Have they mucked up, or is there some legislation here? I'm sure I shouldn't have had that £6.50 back - otherwise why not just sell it all at half price (especially since they do a 5 litre tub as well as the 2.5 litre...)?