Kelkin have reduced their pack weight of their natural micro popcorn from 3x100g to 3x90g while the leaving the box size the same. Tescos and Dunnes are still (incorrectly) caluculating their unit price based on the old pack weights.
I have found alot of the unit prices to be incorrect as I buy nearly everything now based on this: Tescos staff on complaining dont really care....Dunnes Iv found dont even understand what Im talking about (their staff appears to be getting younger everytime Im in there).....
Yes, this is the reason Ive stoppped complaining to the floor managers. To be fair I think the big groups Kellogs, Nestle, Heinz etc actively promote "unit price" confusion. They do this by having a bewildering array of weird pack sizes, "BOGOF's" and 50% extra free stamped on the pack at the point of manufacture.
I have reported similar cases to the consurmer agency (before they were amalgamated) but the young man I was dealing with did not seem to understand the concept of "unit pricing" either! And it is very difficult to explain over the phone.