Draft for legal review. This is not a statement that a lawyer has approved the text.
Deposits and refunds
On a standard approved job the deposit is 10% of the approved total including GST. The balance is the approved total, plus approved variations, minus payments already verified.
A commercial contract can use different terms. The 10% rule is not forced onto an account whose signed terms say otherwise.
Refunds are made back through the original payment provider where that provider allows it. A browser receipt is not enough; the payment must be verified on the server.