Won’t return a item

I bought a dress at The Fix in Promenade on the 22nd of September and I never fitted it on at the store. And on the day I was wearing it I realised it was a bit small for me and I couldn’t wear it again. Today is the 12 October and I tried bringing it back because the item isn’t damaged I just no longer have the slip and tag as I assumed the item would fit. What is the point of keeping store copies for receipts if you won’t even bother helping customers. Clearly TFG doesn’t really prioritize their customers as they claim do. And they probably don’t care because they service the black majority!!