Hello and thank you for your question.
If the contract was for an entire bathroom renovation and payment is not due until completion, then strictly speaking the contract will not be completed until it is completed to a reasonable standard and payment can be withheld.
However, should the builder in such circumstances be unable or unwilling to complete the building to a mutually agreed standard, they could apply to the court and the court would almost certainly order payment of the contract amount less any outstanding rectification cost to remedy any shortfall. So as a builder, whilst it may be an issue for you to secure payment from the customer initially, if you are ultimately unable to finish the work to a standard that satisfies the customer, a court will still order that you will effectively be paid for the value of the work actually done to a reasonable standard as assessed by the court. If the court agrees some of the work needs to be redone then the court would apply a discount to the original agreed price, but conversely, if the court is satisfied the work was satisfactory or completes the obligations under the contract, you would be ordered the full amount.
If the court feels the customer withheld payment unreasonably, the court may also order interest be paid on any amount that should have been paid earlier.
I trust this assists your understanding.
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