Struggling to get my refund back from SHEIN

My child placed an order in December 2021. We did not receive the goods as Buffalo Logistics told us that we paid the excise duties too late and that the goods had been destroyed. They advised that we contact SHEIN for a refund. We did and SHEIN promised to reimburse us. They claim to have done so on the 1st of April ‘22. We’ve checked with our bank and they’ve confirmed that no refund or even an attempt to make a refund was made. It’s now more than a month later and I’m still out of pocket with no goods. SHEIN refuses to send me appropriate proof of payment showing the refund. I’ve even asked that they escalate the matter to someone I can speak to instead of the constant messaging that’s getting us nowhere. My request is for someone at SHEIN to please call me so we’re able to resolve this matter.