I would suggest you deal with this as an ambiguity under Clause 17.1. The PM is then obliged to respond within the period for reply and if he doesn't, that would constitute a CE under 60.1(6).
60.1(3) would only come into play if it was identified at an early stage that further drawings would be issued, and the date for doing so was shown in a programme which had been accepted by the PM.
60.1(3) would only come into play if it was identified at an early stage that further drawings would be issued, and the date for doing so was shown in a programme which had been accepted by the PM.