Item suddenly out of stock on the day its supposed to be delivered. Very poor service delivery

How can you have a customer order a product online and pay for it. a week later when it is supposed to be delivered, I enquire about it. Now suddenly I am told the order was send to dispatch but there is no stock. it showed stock when I ordered. I was also told the order cannot be send to another store, so now it will be a refund. I didnt order from a specific store, I ordered online. For the past 5 days the status showed available and "Your order is ready, our delivery partner will come to pick it up soon". What happened to the service Leroy Merlin used to have. This is so bad.