How Pathetic is your customer service

My dad bought baby formula Friday 23 October 2015, when he gave it to me I saw it was the wrong one . So obviously I could not use it and decided to take it back to the shop. As I stood there at returns counter I was told so rudely by this cashier that if I don't have a receipt she can't do anything. So I asked her what must I do with this wrong milk formula should I just give it to my baby and he becomes ill or should I throw it all out on the floor and waste it. She rep**** sir, you can do anything you like. I then by this time so so upset that I immediately asked for the manager. He came after ten min already so upset he just said no No slip no refund. I laughter I told him that I do not want a refund just exchange for the correct baby formula milk. I told him my father bought this and it was the wrong on. He was adiment there was nothing I could do. He had such a rude attitude and was so unhelpful that I told him I will not leave it like this. Which he the then rep**** I don't care who ever you tell I am not scared. I was so angry I did not take his name i know exactly how he loooks. As I shop there often and always see him. How unfair and pathetic os that customer services.