My Zara Order Was Delivered Incomplete

I placed an online order with Zara (Order #5301*****11) for two vests, but I only received one of them. Zara insists that the reference number 3548/251 item was delivered, despite the fact that the missing item was reported. There has been neither a product replacement nor a refund issued. Requesting delivery of the missing item as well as a refund as soon as possible. In that case, I will exercise the rights afforded to me by the law.