Unhappy customer who was denied refund yet had a slip as prove of purchase

Bought a school shirt January and it was too small for my boy and i wanted another size and i was told that it was the biggest size they had. I didnt get a chance to take it back as i am not around most of the time however i went to the store yesterday for a refund the cashier was willing to help but she needed authorize from the manager of which was not on duty and the person who was on duty came and she told me that they cant help unles i come back the next day so that it can be authorized by the manager.. I understood and i asked my aunt to take it back today and she was told that they cant assist her whether with cash refund or an exchange for its been 3 months since it was bought.. I feel that this is unfair for me for i have a slip the shirt is still in good condition and im denied a full refund yet they are able to authorize exchange without slips.. For that Exchnge without slip who knows that it might be morethan 3months? I am not happy at all for the service we got from jet fochville. And i know that it is possible for us to get a refund for i have worked for retail and in management position so there is no such thing as it cant be refunded or exchanged.