We may at our sole discretion apply the money that you have paid against invoices raised or debts due to us in the order in which they occurred (being against the oldest debt first). 4.33 You shall provide us with a fully completed and signed proforma installation / site ready certificate ("Certificate" ) prior to the required installation date (which shall be at our sole discretion) where we are arranging the installation of WS Goods supplied to you.
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