Fat free milk in a Full cream box

I bought two boxes for full cream milk for my kids for breakfast... upon pouring the milk in their cereal bowl I could see the was something strange with it. I opened the second box to compare and the first one was very light. Considering the fact that my entire fridge is filled with c***** products I will not tolarate this nonsense!!! Life is expensive to be wasting money to nonsense we didn't buy!!!