Unavailable Zara Products and Discourteous Customer Service

Zara promoted a product for sale, received payment, and subsequently canceled the order because it was not available. So if it wasn't available, why was it even listed for sale? When I reached out to customer service, I received a dismissive response that felt like they were making fun of me. Now I'm curious, how can I have confidence in future purchases? Are they going to get canceled as well? I have some reservations about this. I think it would be a good idea to take products off the shelves if they're having stock problems. That way, we can avoid more unhappy customers.