Change in Scope resulting in unavailability of subcontractor and CE for time

NEC4 Option B Contract.

EWN issued by the Contractor that designed gas main route was not achievable due to clashes with drainage. A second EWN was issued 8 days later with the same information but highlighting that gas needs to be installed by 15 days from the date of the second EWN. Works to install gas main were not identified on the Accepted Programme at the time of EWNs and the PMI to change Scope of gas route.
Actual works identified to in a subsequent programme (not accepted yet) show the time required for install is 16 days and commissioning to allow gas switch on a further 5 days. This seems to suggest that the dates from the second EWN were not achievable.
A PMI was issued to change the Scope of the gas route 15 days after the second EWN (23 days after the first EWN)
Correspondence following the PMI said that gas install could commence 8 days after the date of the PMI (this was caveated with note advising further delay to this date may occur due to subcontractor being committed to respond to emergency call-outs for the gas supplier. Delays continued in this manner with final install of gas and commissioning complete some 98 days after PMI.
Contractor is claiming CE for time for the entire period due to change of Scope, which caused them to miss the original planned install date for gas (albeit not shown on any programme).

Is this a valid CE for time under 60.1(1) and should the extended delay be compensated to the Contractor as a result, or as 26.1 does the non-availability of the subcontractor become the responsibility of the main Contractor and therefore should the time claimed for the extended delay not be accepted?