Firstly I'll note that neither party appears to have been operating the contract correctly, the early warning procedure is designed to be used to decide what is required to be done from an operational point of view, you have both been using it to decide commercial matters.
Assuming you're talking about NEC3 ECC with Option B then it sounds like you are correct that this is a CE - clause 60.4 describes the situation you appear to be in. Again, it doesn't seem like the CE procedure has been followed correctly either - notification, quotation, assessment and implementation - whereas this appears to have been done via the early warning procedure.
The PM does have the right to assess the CE in certain circumstances (clause 64.1) and once they have done this and the CE is implemented (clause 65.1) then the assessment is not revised if a forecast is wrong. However, this can be interpreted to mean that assessment can be revised for other reasons. If the PM refuses to accept this then your only recourse is to adjudication, which you should do if you stand to lose a significant amount of money, otherwise you may just have to live with it. The fact that the PM has been assertive in exercising their rights in the contract does not automatically mean that mutual trust and co-operation has failed either.
Assuming you're talking about NEC3 ECC with Option B then it sounds like you are correct that this is a CE - clause 60.4 describes the situation you appear to be in. Again, it doesn't seem like the CE procedure has been followed correctly either - notification, quotation, assessment and implementation - whereas this appears to have been done via the early warning procedure.
The PM does have the right to assess the CE in certain circumstances (clause 64.1) and once they have done this and the CE is implemented (clause 65.1) then the assessment is not revised if a forecast is wrong. However, this can be interpreted to mean that assessment can be revised for other reasons. If the PM refuses to accept this then your only recourse is to adjudication, which you should do if you stand to lose a significant amount of money, otherwise you may just have to live with it. The fact that the PM has been assertive in exercising their rights in the contract does not automatically mean that mutual trust and co-operation has failed either.