I have an NEC3 ECC Option B contract with an unusual amendment.
In Clause 63.13, the bullet point permitting “a changed rate” has been deleted in the list of amendments. 63.1, however, has not been amended.
For CEs for which there is an item in the BQ (and the contract Schedule of Rates, which also has been inserted into the first bullet point of the amendments) for items of work not already done, does this mean that the rates in the BQ or SoR take precedence over any Defined Cost plus Fee valuation of the CE?
Neither ! This clause is about how changes in the Prices - worked out under 63.1 - are inserted into the existing BoQ - see the opening sentence of 63.13.
What it does lead to, which I think you have picked up on, is a contractual dead-end in that if the work is of the same type and quantity as the BoQ, but done in different circumstances (say a more onerous constraint due to an instruction changing the Works Information) which makes it more expensive, then the contract is not clear about how the new rate is inserted into the BoQ.