Taking customer payments for "unavailable" products.

But for one, I've actually had positive interactions with Audico. The one time that they mess up, they really mess up good. Undoing all prior positive interactions that I've had with them. Audico is a retailer, they don't manufacturer anything, service and price are the two metrics which they can be measured on and what will distinguish this from their peers. I made the purchase for order #24134 as a result of the extremely attractive price but little did I know, they were actually advertising a product as not only being available for purchase but on sale , did they did not have in stock. Is this common practice or a genuine mistake on their part?

Can I hold them accountable to delivering said product to me, irrespective of cost to them as I've already paid for the product?