Consumers are entitled to expect that the seller actually intends to fulfil their advertised promises, in other words, that the product is available when the advertisement is released.
If a discounted product is sold out, the customer must at least be given the opportunity to purchase it at the discounted price at a later time or to buy a comparable product instead. Other compensation requires consideration of how carefully the business conducted its discount sales campaign, as unexpected turns of events are always possible. Stock-outs can happen despite precautionary measures or because of genuine mistakes in advertising. If a discount sales campaign is carelessly planned, the business must compensate for the customer's travel expenses arising from the needless visit. If there is evidence of clear neglect in the planning of the discount sales campaign, the customer may even be entitled to make a so-called cover purchase, which means buying the product elsewhere and claiming the difference in price from the seller who advertised the discounted product. Advertisers must then take sufficient precautions to ensure that the stock of campaign goods is large enough to last the entire duration of the discount period. The condition "as long as stocks last" can only be used in advertising under exceptional circumstances.