Once upon a time I bought a multipack of Walkers crisps on offer [naturally squeak squeak]. All was well until I got to the last packet which was full but sadly only full of air. Hardly important on a world stage but they had a freefone number on the back so I decided to just cheekily give them a ring and let them know. I thought it would be difficult to prove that the packet was empty but apparently every once in a while one of their packing machines goes into overdrive and zealously seals the odd empty packet. From the codes on the back that I read out to the lady from Walkers she was able to tell not only which factory had produced them but also which line and the specific machine. Normally they hoick them out but occasionally one slips through. I received a very pleasant letter from them and vouchers and they meanwhile were able to run a check on said faulty machine.
Last night I was chatting to a gentleman who in a similar vein made a light hearted observation. When he goes to the cinema he likes to buy himself a box of Smarties. On this occasion there were no orange ones which are the only flavoured ones these days apparently. He bought a second box which he emptied out at home to carry out his own research which resulted in a two page letter of formulae listing the probability of there not being a single orange Smartie in the box [he's a teacher]. Having sent if off to Rowntree [as they were then] he heard nothing. He drew that conclusion that the company perhaps hadn't seen the funny side....several weeks later the postman delivered a big parcel to him. There was no accompanying note just a big box full of orange Smarties! I like those sort of tales!