worst manager in retail

I bought a baby sound from baby boom,used it twice and it stopped working. I bought batteries used it once and it stopped working. I assumed maybe there's something wrong I was doing.Fortunately I had the slip as I bought it on the 6th March,on the invoice it only stipulates that there are no cash refund however you may exchange goods but there's is no time frame stipulated .I went there so calm, got to the door and asked the guy to check for me whats wrong with the item,as I was speaking to him he notified an old lady assuming it's the store manager. She asked for my invoice and first thing she said is we can't take it back,my response was who said you must take it back cause I just said please check what's wrong with the item. She rudely responded I left the item there to avoid drama. I will escalate this as further as I can.my contact details are ***