"How often has a purchaser been told by a repair shop or other supplier of services: "This is taking longer than we expected..." or "We have had a cost overrun on supplies so we will have to charge extra to complete the contract."Giving more money for no better service, or accepting late delivery when promised something earlier is clearly past consideration, or no consideration at all. How do you think this should play out between the parties legally and ethically, and what would represent good business practice? Does it matter to your answer if such events for any given business are very rare or very frequent? "

Discuss. In your response, define "past consideration" and "consideration".