Refuse a refund

I bought small carrots purity foods at Three rivers and i wanted big bottles then i went to Cherckers Arconpark to excahange which ii managed to do but the took my receipt for their records provide me with the new one for the exchanged purity. I went with my baby to the clinic to consult because she was constipated i was told that i should avoid giving her carrots and potato because those vegetables they cause constipation , i then had to go back to exchange the carrots for other flavours , then i talked to Paulina at checkers customer desk , i told her that i misplaced the receipt and i want to exchange she told me to go and get the one that i want, when i came back with purity that i needed i was told that they cannot exchange because those bottles because i dont have a receipt , when i asked wgat must i do with those purity because my baby she is not suppose to eat that they told me that those belong to me because i bought them i can do whatever i want with them, my baby had to sleep without food last night , i was not undermined it was an inconvinience and also a waste of time. please help