He should always comply with the deadline. Failure to do so makes all his efforts fruitless. So though he delivered the product it was of no value to the customer as he had run out of time and had made other arrangements.
In the case provided it's not mentioned that the contract between Alf and the customer was written or not. If the contract is written then legal action can be taken against Alf. Since verbally the customer has mentioned that he cannot work other than the stipulated time, he has all rights to take action against Alf. The written agreement between both the parties with a clear mention of the time makes Alf's case weaker. However if the customer does not have a copy of the written agreement between him and Alf then his case becomes weaker. Also if somewhere in the contract if it's mentioned that the shopkeeper is in no way responsible for any delays in delivery then too, the customer can not take any action against Alf. So though verbally Alf and the customer know about their agreement, if the customer has a written document then Alf's action can be proved a legal offence. So for the sake of law it is advisable that Alf does not impose the contract forcefully on the customer.
In the second case the customer was unable to work with an ...
After inspecting the gravity of the defect, the seller should replace the product, repair the fault or in extreme circumstances even refund the money if the customer is not ready for either replacement or repair. But he cannot say 'no' to the customer. Hence legally the customer can take action against Alf for not complying with the guidelines of selling electronic gadgets. In such circumstances it is advisable for Alf to refund, as he himself will not have to suffer any losses because the sellers have back-to-back service and maintenance contract with manufacturers. According to Kolah if the customer claims that the purchased product is not working properly then "Such a claim will require the interpretation of the defendant's obligations under the terms of the contract. This is because there may be express terms of an agreement the claimant and defendant concerning the purpose and standard of the product." (2002, p. 52) If it's not this, then to ensure that the product is fit for the purpose made known to the seller, in the contract terms, the law implies that the product is of good quality and is appropriate for the buyer.
In the third case too, Alf has the similar legal bindings as in the second case. Alf assured the customer at the time of sale that the saw he is selling is meant to cut anything, even steel bars. Since the saw broke down on the first day of its use, the case of misrepresentation of facts by the seller can be charged on Alf. He is liable for refund or replacement and if he is not willing to do so then the customer has all rights to drag him to court. If the seller is making a statement to the potential buyer, like in this case, according to Kolah