Upselling

Upselling was the practice of trying to make additional sales after a customer has already made one purchase. The Kerb!am Delivery Bot version 1.0s were programmed to upsell when making deliveries. When the Thirteenth Doctor reactivated one it offered her ear mufflers, pencil sharpeners and cola bottles, saying that if she bought all three then the cheapest product would be free. (TV: Kerblam!)