i have something to contribute for once! i work nights at a supermarket, and they had been calculating the store's holiday pay wrong for years, knocking about 15 minutes of pay off each holiday payment. however because they had no way to check who was entitled to what, they just gave out payments to people based on what they think they should have (based on number of hours worked a week and how long they'd been there). i was new to nights (2-3 months or so), but they rounded me up to 6 months as a minimum, and i got about £90 which i shouldn't have got ^-^
on the flipside, my girlfriend got underpaid, they put a decimal point in the wrong place, so for an overtime shift she got paid £11.40 rather than £114... she claimed that error back, naturally