Builders online sells out of stock items

This morning I ordered and paid a Elba Gas heater on Builder's website. After the transaction I received a survey which asks about my online shopping experience. It had been a very smooth one so I gave them positive answers all round. This afternoon however, I receive a call from them to let me know there isn't stock. I am very, very unimpressed. What kind of an online store does Builders run? I asked the person if they don't have another colour in stock but she couldn't tell me which I think is super unprofessional. If you are about to disappoint a customer, you should be ready with alternatives or at least have the answers ready. She said she will call me back. A very fast check showed ne that they are out of stock, yet still possible to buy!!! What? When/if she calls back, I'll cancel my order whether they have or don't. And I will never set foot in a Builder's again.