NEC ECC: When should the CE have been instructed?

Thank you for answering Rob, however it appears that I have not provided enough detail for you to answer in the way I had perceived the answer to be; it does not concern the legitimacy of the rate itself but the time of which it should have been instructed and possibly by whom in order to determine the effect on planned Completion. Unfortunately I can’t upload a timeline file so I shall have to summarise as follows:

April - Work Carried out
Early May - Additional Work Identified
Mid June - Valuation reduced

Conversations surrounding validity of rate between mid June and Early July

Early July - Existing Rate identified as incorrect
End July - PM instructs new Item descriptions to be priced

We are all in agreement that it should be a new rate, the question is when should the new item description have been instructed? Due to the long delay between the work being carried out and the instruction, is there not a case to say the instruction should have been made sooner? If so when? The rate has always been incorrect so at what point should the parties have known?

The issue arose when the PM wouldn’t pay for the work carried out due to overbreak, he stated that it should have been included in the rates, that’s when the existing rate became insufficient. However the rate has always been the wrong rate.

I need this date to determine which Accepted Programme I use in order to assess impact on planned Completion.