In July, Byan booked and paid in full a 14-day's exclusive package tour to Wing Long Travel Company ("Wing Long") for visiting Machu Picchu in Peru, one of the New Seven Wonders of the World. In order to join this tour, Byan gave up a free-lance job valued $15,000.

On August 16, three days before the tour commencement date, Wing Long informed Byan that the tour had to be cancelled as the Peru government had closed the Machu Picchu region and prohibited the entry of all tourists due to heavy snowstorms. The severe weather was expected to last for two weeks. Snowfall in Machu Picchu is extremely rare, particularly in summertime, because Machu Picchu is located in a tropical cloud forest, and the average temperature ranges between 12 and 26 over the year. Thus, there was no provision stated in their contract regarding how to deal with it.

Wing Long then offered to refund the tour fee in full to Byan. However, Byan refused to accept the refund and would like to sue Wing Long for the breach of contract and claim damages, i.e. the tour fee and the loss of free-lance job valued $15,000.

Required:

In the context of contract law, advise Wing Long of the possible defence available in case it is sued by Byan for breach of contract.