Jennifer decided to update her ensuite. She signed a written contract with Whale Constructions Pty Ltd (WC). This contract gave her a certain amount of money to spend on taps. Jennifer chose a particular style and brand, which she believed was within her allowed budget, and informed WC of her choice.

When Jennifer was checking some invoices, she saw WC had invoiced her for an above budget amount on the taps. When she queried this John, from WC, explained that the tap model she had requested had been discontinued and that the tap style which replaced her model were the ones installed and she had said nothing at the time of installation. These new taps were more expensive. Jennifer refused to pay the extra money arguing WC should have advised her of the change and sought her specific approval before installing something else.

Advise Jennifer as to her rights using contract law principles only in this situation.