Zara Shipping Returned, No Stock for Refund

It's kind of surprising that a big brand like Zara is having trouble with product supply. So, get this - on the day of delivery, the shipping company said they couldn't drop off the package at my place and ended up sending it back. Can you believe that? So, I contacted Zara and they're telling me that they can't process the return because they don't have any stock left. This is the first time I've encountered such a problem with Zara. I just can't wrap my head around it. The item is still listed as available on their website. I'm having trouble finding someone to talk to about this problem. I won't be shopping from this brand again, that's for sure. Can I please get a refund as soon as possible?