Could you please help me with this business law question:

Wilona was married to Wilbur for 40 years. She was devastated when he passed away. She

had been very reliant on him and left all their business matters to him. She had always been

a religious person and turned to her faith for solace.

She was visited by her local priest, Father Devout. She talked about her situation with him

and concluded that she should sell her matrimonial home and move into a small unit. Father

Devout was himself looking for a new home after the church had informed him that it would

be selling the bungalow adjacent to the church building in which he currently lived as a cost-

cutting exercise. He mentioned this fact in passing and Wilona insisted that she sell her house to him. When he asked how much she would want for the property, she said she had no idea

of its worth. However, she had heard a neighbour say that a house in the street had sold for

about $200,000, but, because she knew that her house would go to someone deserving, she

would sell it to him for $100,000. This was in fact half its true value. She wouldn't take no for

an answer and Father Devout knew her to be someone who would obstinately insist on

something once her mind was made up.

Wilona needed a bridging loan to purchase her unit. She does not trust banks and instead

approached Sly, a fellow parishioner. Sly was a wealthy businessman, who told her he would

give her the necessary funds if she signed a receipt for it so he 'would have something to

show the taxman'. In fact, the "receipt" was a basically-worded loan document, which

provided that she was liable for interest at twice the rate that she could have obtained from a

bank. Wilona signed the document without reading it because she thought Sly, as a fellow

churchgoer, was "a good man".

Wilona's son and daughter have just flown in from their respective homes overseas and

discovered what Wilona has been doing. They seek your advice on whether she can undo

what she has done.

Need help for Wilona's children, discussing all available grounds for relief under Australian contract

law.