Bad service ever

So it was advertised on Sunday noon that the boxer stores they having a black Monday to buy 4 packs of Nutriday danones and get one free, rushing to work on Monday I got to the store and bought the danones for my son and went to work. Later on I check the expiry date randomly to find out that twelve of them were expiring same day then 18 is expiring on the 02nd December. Today in the morning I went to store hoping I will get an exchange or refund, the floor supervisor exchanges 6pack and gives me the 8th as expiry date and was told the rest can't be exchanged as they have few days to expire, then i was called in the office by the manager to be told he knows what I'm trying to do I must listen to him carefully he will only give me with a cheaper price take it or leave he didn't listen to anything i had to say, in the store they had the ones expiring on the 23rd December which I asked for, he refused straight to my face saying he won't be able to assist me. I left the store and their danones.