is it just me? in shops and the like only the last year or so- is it rife? for example i hand over a £5 note but my change is a quid short. it always happens when the place is busy with a queue behind me so im urged to move away from the till let next person get served and only then realize im short-but by then feel its too late to kick up a fuss. its always a sharp type middle aged slicker at the till, not the ageing granny sort.
get your own back.
go to a macdonalds or kfc type drive through.ask the brain dead at the till if he has change for a £20 then hand over a £!0.
guaranteed 90% of the time you get your change back plus an extra £10…i do it anytime my misses is in the car with me purely for the fact that shes mortified. 
When I was a teenager, about 18, and I took a girl out to a travelling funfair- Only to find out the hard way that you NEVER give the Dodgems guy who goes prancing around on the back holding onto the electric stalk - anything but the exact money… 
I was daft enough to profer a William Shakespeare £20 note for a 2x£1 fare for the ride. 
You know what it’s like as a teenager… U don’t wanna show the girl a fiver, or a pack of ten bensons - ’ cos it makes you look like a teenager on pocket money, rather than casanova on steroids which was the effect the big crisp purple beer token I pulled out was supposed to have. 
Brudder Guy comes back from “Breaking my big note” and chucks a huge pile of shrapnel into my lap, 
(Girl and me are sitting in the dodgem car) I could see that this weighty mass of metal included the old Deutschmark-sized 5p bits, and coppers that even had old 'hapennies with the ships on them… … Couldn’t get to count it up there and then of course… After the ride, I took it straight to one of the small “amusement arcade setups” where they’ve got those bored looking women pushing stacks of 10p coins at people - only to find that there was barely £12 in small change there - not very good for change out of £20 for a two quid ride! 
And I’ve never trusted nor liked the brudder brigade ever since.
I pay mostly via card now I rarely carry cash on me if ever.
Heck our currency stop actually being worth anything ages ago they are even making the coins plastic now so might as well use card.
Winseer:
When I was a teenager, about 18, and I took a girl out to a travelling funfair- Only to find out the hard way that you NEVER give the Dodgems guy who goes prancing around on the back holding onto the electric stalk - anything but the exact money…I was daft enough to profer a William Shakespeare £20 note for a 2x£1 fare for the ride.
Brudder Guy comes back from “Breaking my big note” and chucks a huge pile of shrapnel into my lap,
And I’ve never trusted nor liked the brudder brigade ever since.
You’re lucky you didn’t get a ‘bunch of fives’ back for giving a note ten times larger than the amount due! 
When I’ve dealt in cash, I’ve often kept (correctly pre-counted…) “punishment bags” of small change ready for such punters.
Winseer:
When I was a teenager, about 18, and I took a girl out to a travelling funfair- Only to find out the hard way that you NEVER give the Dodgems guy who goes prancing around on the back holding onto the electric stalk - anything but the exact money…I was daft enough to profer a William Shakespeare £20 note for a 2x£1 fare for the ride.
Brudder Guy comes back from “Breaking my big note” and chucks a huge pile of shrapnel into my lap,
And I’ve never trusted nor liked the brudder brigade ever since.
The important thing is, though, after all that… did you get laid?
I use Wiatrose in Deptford on a regular basis and very seldom checked the receipt or even said yes if offered one but one day I kept and checked it and it stated a £10 cashback !! No way on earth would I just want £10 in me wallet. Went to customer services and got back the tenner within minutes. Funnily enough haven’t seen the assistant who served me since then … maybe she tried it on once too often