I have an problem-based situation on Business Law, please help me to solve this:

"Billy is keen to start his own business selling frozen pizza on-line using the internet.

He decides to advertise his pizza by using the daily newspapers. In the advertisement he states as follows :-

High Quality Frozen Pizzas available for sale

We accept orders on-line at www.frozen-pizza.com.

Place your order now and receive a 50% discount off

the original price of $20.00 per packet.

Terms and conditions apply.

Bob is going to hold a party soon. He sees the advertisement and is keen to buy the frozen pizza. Bob goes on-line to Billy's website. However, he is unable to click on the 'place order' icon. There is a phone number displayed on website with a statement inviting customers to place orders through the means of sms text message.

Accordingly, Bob places the order for 20 packets of the frozen pizzas via sms text message and sends the text message to Billy.

Unfortunately, Billy is away in Malaysia and his handphone does not have an auto roaming facility. As a result, he does not receive the sms text message sent by Bob.

As Billy did not receive the sms text message from Bob, he fails to make the delivery. Bob waits till the night of his party and is angry at the non-delivery. He calls Billy and threatens to sue him."

Please give advice on how to deal with this problem to both Billy and Bob.

Thank you