A retired Polish couple, Mr and Mrs Piotrowski, with little understanding of written English or formal education signed a guarantee and mortgage over a block of shops to Ocean Bank as security for payment of the debts of their daughter's company. Their daughter was a sole director and majority owner of a property development company. At the time of signing, they were led to believe by their daughter that the guarantee and mortgage were up to $65,000 and limited to eight months. They were also told by their daughter that the company was solvent, when in fact it was insolvent.

When the bank manager brought the documents to Mr and Mrs Piotrowski's home for them to sign the mortgage and guarantee, he corrected their misunderstanding about the length of time the guarantee was to run for, explaining that it was for an indefinite term and not eight months. However, he didn't explain the possible legal impacts of the documents, which the Piotrowskis could not read, and he did not mention the fact that the amount guaranteed was unlimited. When the daughter's company went into administration and the bank attempted to exercise its rights under the mortgage/guarantee, the Piotrowskis sued them in court to have the contract voided.

Can the Piotrowskis successfully claim against the Bank under the Australian Consumer Law? If yes, under what basis can they claim?

Please explain the answer using IRAC method and academic references.