Shein Denied Refund Claiming Returned Pillowcases Did Not Match

I ordered a set of four pillowcases from Shein in June, with order number GSO17564R00MG6W and item SKU sf2409091542203580. The product was supposed to be a pink milk velvet pillowcase set, size 50–75, but what I received was purple instead of the pink color I wanted. The order was delivered to me in England on 14 June and I returned the items on 19 June. I would have returned them even earlier, but I was busy, and when I requested the return, Shein sent me an email instructing me to pack everything together in one package, which I followed. Later, when I contacted customer service about my refund, I was told that the item “does not match,” and for this reason my money was not refunded. This is confusing and unfair, because I simply returned exactly what Shein sent me, just in the wrong color, within a very short time after delivery. I am requesting a full refund of the amount I paid, to my original payment method in pounds sterling, as I correctly returned the pillowcases according to the instructions Shein provided. I ask that this issue be reviewed and my refund processed as soon as possible.