Contra-charges have appeared from nowhere

It is a familiar pattern: nothing said all job, then at the final account a schedule of set-offs appears, for attendances, alleged defects, supervision, delay, often round numbers with no build-up. They are deducted first and justified later, if ever, because the payer holds the money and the burden of dislodging the deduction quietly shifts to you.

That is not how set-off works. A deduction needs a contractual basis, the notices the contract and the Construction Act require, and evidence behind the number. Charges assembled at the account stage often struggle on their own paperwork, and each one that falls goes straight back onto the closing balance. The work is unglamorous, charge by charge, and where disputed accounts are usually decided.