Tom, a local motor-bike mechanic, needed ten mufflers for the Handa GTX2999 bikes that he was doing work on in preparation for a local motorbike competition. He telephoned the manufacturer asking if the parts were available. After checking, the manufacturer told Tom that they had a box in stock which they would sell to him for HKD20,000 and "if you want them, telephone us by close of business this coming Friday". On Thursday, Tom wrote to the manufacturer requesting the box of mufflers and gave his credit card details. Due to delays in the post, the letter did not reach the manufacturer until the following Monday. On that day the manufacturer telephoned Tom and told him that they had sold the box of mufflers to another customer but they were willing to supply another box but at an increased price which would take about a week be delivered to Tom.

Using the PIRAC method, is there a valid and enforceable contract between Tom and the manufacturer to supply the box of mufflers for HKD20,000? Advise Tom and the manufacturer as to their respective rights and liabilities. Please refer to relevant cases and legal principles in your answer.