Refund dispute

I purchased items on the 14th December 2021 and when I was supposed to receive my order Buffalo Logistics lost it. I app**** for a refund on the 18th January 2022 and I still haven’t got it till this day. Refund amounting to R701. They told me to go check with my bank because the refund was processed on their side. I’ve been to my bank countless times with the transaction reference number Shein gave still nothing. If they say they have processed the refund why isn’t it in my account?! How can the bank help me when the money wasn’t processed on their side?! Shein stole money!