NEC ECS: Option A, no subcontractor rates have been advised to the main Contractor

An option A contract, no subcontractor schedule or rates have been advised to the main contractor. Late in the project the main contractor is unhappy with our subcontractor cost plus fee and requests we use our rate ( which is less ) for the price of works. Would this still stand at subcontractor cost plus fee?

Can you expand upon the circumstances a bit. E.g. :

  • where do these rates come from which the Contractor wants you to use later on in the contract ?
  • this is for a compensation event as opposed to original work (which I assume you are being paid for under the activity schedule ) ?