Final answer:
The best course of action would be for the buyer to send the seller a letter asking for assurance that the seller will perform by the contract date.
Step-by-step explanation:
The buyer would be best advised to send the Seller a letter asking for an assurance that the Seller will perform by the contract date. This would allow the buyer to express concern about the potential delay in delivery and request confirmation from the seller that they will still be able to fulfill the contract.
This act of reassurance from the seller would help alleviate the buyer's concerns about the possible breach of contract. It would also provide the buyer with a written record of their request for assurance, which could be useful in the event of a dispute.