Maintain Plan date

Hi SAP Experts,

In maintenance plan I used scheduling indicator Time-Key Date with call horizon 95% and ticked Completion requirement. Start of cycle was 08.03.2016 and it is maintained with 2 month package.System gave correct scheduling.Now what happened system generate first call date on 05.05.2016 and plan date is 08.05.2016. user also have done preventive maintenance on date.But in system due to some reason user close the call on 27.05.2016.Because of scheduling indicator Time-Key date ,system will change the next plan accordingly call close date.

Now user want that plan date should not be changed , due to some reason they could not close in system but did preventive on time.The query is that,how we can control this type of case.

PlanDate    CallDate     Completion     Pack

Thanks

Regards

Gaurav Solanki