PEP Store Wonderboon junction treated me like a *****.

I bought a onesie for my two-year-old daughter from the grove Pretoria, unfortunately, I made a mistake and took a smaller size. I went to different PEP sores to look for a correct size for her, but I couldn't find it. Just when I was about to give up after 3 days, I went to PEP Wonderboom junction, and I got the correct size. when I was looking for my slip, I couldn't find it, but the price tag was still intact. I went to the shop and there was no security guard at the door, I went in and took the correct size and went to the till, upon arrival ,there was a gentleman who I explained to that I have no slip but the tag is still in tacked, he then said I was supposed to tell a shop assistant that I'm returning something before I could get a correct size, I did not know this because normally when there is no security guard at any shop , you just walk in and take an item and exchange him and the manager insinuated that I stole the item and now I want to exchange it, I told them that they can check their cameras and they refused, they said they cannot help me. The advised that I should go back to where I bought it from, petrol is expensive that's number one, 2. I did not like how they treated me like a ***** who possible entered the shop with an item without a slip, things happen and it was unfortunate that I had lost the slip.