I was robbed my money

Today the 12/06/21i went to the above mentioned pharmacy since I bought sinutab medication on the 08/06/21and when I got home it was expired,I went back to exchange today,as I approach the white lady at the till,they were two and the younger one greeted me and I responded,and hand in the medication to say that I brought it back,without her asking me why did I bring it back,she started shouting at me and I showed her the expiration date,with loud voice she ask me if I want my money back I said yes,she went into one small room and came back saying her boss said I cannot get my money back,then I said to her if you have asked me if I wanted to exchange without shouting at me I would have said yes but know I want my money and demanded to see the boss,the boss was the pharmacist of the day and he told me if they open the till and give me back the money it will be like she is stealing though I had a receipt and the medication back,I was highly disappointed at the whole situation and I was given the option of leaving without the medication and money,because iam a peace maker I gave both to them let them win and I will loose since iam stupid.