This annoyance with getting bottles of beer and taking the bottle back to get it cheaper next time is really confusing, you get charged more initially, but sometimes you don't. What is going on? Next time I'll try to remember to take my old bottles but for now I just bought 24 cans of Brahma extra, it was only $5000 pesos for all 24 around £6 or so, good considering its one of the better beers here.