This reminds me of my purchase of milk at Carrefour last week, I bought 2 half gallons of 2% because they were out of skim, the sign on window says buy 2 and get a big discount.. I didn't notice that I was charged full price until getting back to the resort. So this week I took the receipt to the manager when buying milk again and was told that sign was for skim milk only. And in the past 3 years I've bought milk there twenty times or more and have never seen a sign designated skim milk only.
Maybe now they will list what is covered and what is not.
A lesson learned, check receipts