Ok. Bought some clothes from a large chain on afternoon of Tuesday 2nd. Decided they weren't right for me. Receipt said "you have 28 days to return any unwanted items to us", no other info. Went back to shop on morning of Tuesday 30th (e.g. exactly 4 weeks later). Cashier refused a refund because "it's more than 28 days, because the day you buy them is day 1". Would only offer a credit note. In my opinion I had had the clothes in my possession for 28 days so was within the returns period (no specific 'return date' was printed on receipt).
YABU - it's obvious that I should have returned them by Monday 29th
YANBU - it's not clear that the day you buy them is day 1 and I should have had a refund