Can I claim gain achieved whilst within a CE

I have a current project in which the groundworks activity was generous in the time allowed and I expected to finish this item in 10 days rather than the 22 contained in the accepted programme.  however after the first day of this activity we discovered unidentified services and a compensation event was raised.  the remainder of the job was in delay but the groundworks continued in unaffected areas and only took the expected 10 days not the 20 as per the initial accepted programme.

the CE for diversion of the services ran on for 70 odd days.  Do I have to deduct the 22 days I had originally allowed in my accepted programme off the 70 days to work out actual cost of site overheads/prelims or can I use the 10days that the activity actually took?  (The contract is the NEC Short Form with activity Schedule.)

The way I am looking at it is the CE negated the gain I would have achieved had the services been as per the works information.  Now instead on being on course to finish 12days early and save the cost of my site setup and foreman etc do I loose the 12 days as the client will claim I had allowed 22days in my original programme?

Thanks

Ruairi