NEC ECC: what happens if an activity is missed from the Contractors programme.

The contract is ECC Option A with secondary Options X15 and Y(UK)2 being incorporated. The Contractor submitted his first programme for acceptance in accordance with the contract timescales but now realises he has not priced a 30m length of security fencing, nor is it shown on the programme.
a. Can the Contractor be paid for this fencing?
b. What happens to the Accepted Programme now that both the Project Manager and Contractor realise there is an error on it?
A month later the Contractor has sent out some enquiries for some subcontracting piling works, which is Contractor-designed to meet a performance specification in the Works Information provided by the Employer. The price is 30% more than he has allowed for in his tender. The Contractor is advised by one tendering Subcontractor that some alternative piling could be provided at half the quoted price and which meets the performance specification for the piling in the Works Information.
c. Can the Contractor change the piling method he has priced upon and shown in the Accepted Programme?
d. On what grounds can the Contractor submit a revision of the Activity Schedule to the Project Manager for acceptance?