NEC ECC : Option A - Lack of detailed information listed within the SSCC

We have recently received a Compensation Event Quotation from our Subcontractor for an instructed change to the Works Information. The Subcontractor upon submission of his quotation has pro-rata the Activity Schedule. This is something i don’t agree with considering the complex changes involved. My next step was to refer to the Defined Costs within the SSCC. However, this is lacking a comprehensive list of relevant activities to enable me to undertake a meaningful assessment.
What would you suggest be a appropriate compromise?

I would simply say follow the contract.

The contract says by agreement you can use activity schedule rates, but if one Party does not agree then you use Defined Cost - which is building up the quote using the elements within the shorter schedule of cost components. You will have to ascertain how many operatives, how long, what equipment etc in accordance with sections 1-6 of the SSCC.