My case is similar.. I have ICT T2 visa valid for 3 years but employer is saying I can't stay more than 2 years since I traveled under dispensation model.
Doesn't make sense to me. Please help as I can't see any clear guidelines on HRMC site.

My case is little tricky. I have ICT T2 visa valid for 3 years from august 2015 to aug 2018 but CoS is valid for 2 years only. Aug 2015 to Aug 2017.
Employer is saying can't extend due to dispensation rule. Doesn't make sense to me.
Can't find any such rule on HRMC. PLease help.