Answered: NEC ECC: What happens to an Accepted Programme if the Project Manager and Contractor realise there is an error on it?

Nothing can be done about the Accepted Programme but the Project Manager can instruct the issue of a new programme (which the Contractor will have to submit within the period of reply).  

The Project Manager can then accept the next programme assuming the error is corrected, or reject the next one if the error is still present.