bad service

I was at shoprite today to buy some groceries ,i paid and left the store just to discover i did not buy milk so i turned around,when i got to the parcel counter i was told they do not allow shoprite plastic bag to be checked in i must go find the security and he must put a sticker on the bag and then i can return with my parcel and she wil except my parcel so i'm wondering how can you run a company like this and keep your custumers happy