Could u please help me to find any law case relevant to this case:

Mr Singh has been running a successful lawn mowing and garden care service firm over the past few years. His business expanded rapidly around Darwin with his business taking over some of rival businesses. He now plans to expand in other parts of the Northern Territory including Katherine and Alice Springs and he needs to raise a substantial sum of money. He views his business prospects as very strong and so does the bank. However, he has insufficient personal assets to secure a large enough bank loan and has decided to ask his elderly mother to be guarantor for his loan application. He needs her to guarantee a loan of $500,000. His father had died some years ago and left his mother the family home which is estimated to be worth approximately this amount. He explains to her how this property could be used as security for his business loan. She is now elderly and is not confident with any documents written in English, but she is alert with a sharp mind. The local Australian bank advises her to seek independent legal advice in the presence of an experienced, certified interpreter before she signs any formal documents guaranteeing her son's business loan. But she trusts her son's business acumen so much that she does not find this necessary, and she insists on signing the guarantee in the office of the bank manager on the spot so her son could 'get on' with his plans. She even signs a document to say she refuses the suggestion of independent legal advice and an interpreter. Less than twelve months later Singh's expansion plans are disrupted with a severe downturn in the economy due to COVID-19 resulting in all his projects suffering. His business is facing insolvency and the bank plans to enforce the loan guarantee against Mr Singh's mother.