Shein Refund Never Received

I placed an order with Shein on June 18 that included several items, among them a pair of pants and a pair of sunglasses. Later, I received a message from Shein stating that a refund would be issued for both the sunglasses and the pants. However, I only received the refund for the sunglasses, while the refund for the pants, in the amount of 19.36 USD, has not been credited. Because I ordered many items together, I am not sure under which exact order number the pants were included, and I did not receive a clear separate reference number for that specific item. I also could not find a phone number or a clear way to contact Shein customer service directly about this issue. I kindly request that the missing refund for the pants, in the amount of 19.36 USD, be processed and returned to my original payment method as soon as possible, or that I be informed clearly about why this refund has not been completed even though I received a message that it would be.