There is no such clause − and doing so would not be acting in a ‘spirit of mutual trust and co-operation’. If your project manager is not happy with the contractor’s quotation they should make their own assessment, see clause 64.1, which will have to be based upon what they think the defined cost should be in accordance with clause 62. The project manager has to provide details of their assessment in the same way that the contractor has to, see clauses 64.3 and 62.2.
If the project manager has enough knowledge to decide that the contractor’s assessment is incorrect, they should have enough knowledge to make their own assessment. When carrying this out, the project manager should be using their own professional skill as an independent and unbiased assessor. Note that unaffordability is not a reason for not accepting a compensation event.