I worked on probation as a teacher in a missionary school but I did not get the arrears as per 6th pay commission

I worked on probation  as a  teacher in a missionary school but I did not get the arrears as per 6th pay commission 

even I forward a letter to them for the arrear but did not get any answer, can u suggest me what should I do further.

please guide me. waiting for your answer.

PREETI GAUR