NEC ECC: Project Manager instructs the Contractor to stop work on a part of the works as, following instructions from the Employer,.

On an ECC Option C Employer-designed contract, the Project Manager instructs the Contractor to stop work on a part of the works as, following instructions from the Employer, the Employer's designer is looking at the implications of a design change. All are keen to avoid any abortive costs if at all possible. After due consideration, some two weeks later, the alternative is abandoned and the Project Manager immediately instructs the Contractor to proceed with the original design layout, well aware there may be a delay and additional costs.
a. What should the Contractor do in order to protect his interests under the contract?  marks
b. What sanctions are there in the ECC for where the Contractor does not notify an early warning?
It turns out that the next day the Project Manager does notify this as a compensation event and instructs the Contractor to submit a quotation. The Contractor informs the Project Manager, two weeks after being instructed to submit a quotation for a compensation event, that it is impossible for him to meet the three week deadline.
c. How should the Project Manager respond?
The quotation is finally submitted in the end within the three week period for submission.
d. The Project Manager fails to meet his two week deadline for replying to this and the Contractor notifies the Project Manager that his quotation is deemed accepted. Is he correct?