Review Selling your item you already bought

Bought tiles on Sat and arranged pick-up Monday, only to be told they "ran out of stock" when they had it in stock when it was sold to me. So no tiles to be collected, even though they are paid for and told this is standard procedure. Not acceptable. So I should wait on a re-order for how many months and stall my renovation project because your stock inventory tracking is non-existent? You just lost a customer.