The subcontractor has refused to provide the quotation breakdown and cites unavailability of commercial resources despite being a major UK subcontractor. They also state that they have provided the best possible price and may not have access to the labour and resources to carry out the works unless it is instructed immediately. Our contract contains a time consuming procedure for identifying and employing a replacement subcontractor due to the identity of the client so failure to instruct our existing subcontractor within the next 7 days will leave us open to creating a delay in the project works. In addition having another subcontractor carry out work on the existing subcontractors scope will create a warranty issue which has further liability implications for ourselves. Are we now in a position where we can contractually Instruct the additional works without an agreed price whether Quoted or Assessed being stated with the Instruction? or is there an alternative solution that does not create the risk of Adjudication on an Assessed value for the instructed works?
You can instruct them to proceed without agreeing the quote, That gets things moving so there will be minimum affect on programme (and potentially price as well as delaying instruction could lead to increased cost). This is covered in clauses 27.3 and clause 61.1 and they are obliged to follow an instruction and proceed in meantime.
Once they then submit the quotation, it is in their interest to break it down into enough detail to convince you it is correct in line with the contract at open market rates and with a sensible risk inclusion. If you are not convinced, then you have the right to ask them for more back up/revised quote or make the assessment yourself at what you consider to be correct fair open market rates given the circumstances. This would then be implemented, and the Subcontractor would have to go through adjudication if they feel your assessment is incorrect, so as long as you make an assessment that you think an adjudicator would agree with then a) you should be ok and b) they are unlikely to go to adjudication on that basis in the first place.
I don’t think you can ever avoid the risk of a matter going to adjudication, only limit it by making correct fair decisions along the way. Statistically it is rare that a matter does ever go that far anyway as you have to be sure you are correct to want to go to adjudication as if wrong and the losing party you would have to pick up all the costs of the adjudicator yourself.