I used to work for Sainsburys (don't shoot me)!
I was a stock controller, and we once phoned up our petrol station from the main store and told the petrol manager that we were doing a stock take and we needed her to weigh the fuel tanks (which are under ground). About half an hour later, she phoned us back asking if we could come and show her how to do it because her scales for fruit and veg weren't big enough!
The powers that be a Sainsburys will nearly always support the customer. Unfortunately, some of the shop floor staff aren't always the brightest. Education is the key here I feel.