India Post — miss manage my ssa account of my daughter

Sirwith great respect your goodself i have a compliant aganist the computer oprater of your post office that is i have opened two ssa account in your post office on ist april 2015 the accounts were run smoothly in the year 2015'2016 but when i deposit yearly amount of 12000 im april 2017 i fill the credit slip of 12000 i am surprised to see they entred 11950 on my passbook they deducted illegly rs 50 from my 12000 when i enquiry about it they did not give satisfy answer however i am not defaulter i deposit every year the amount on fixed month ie april they also did not make the entry of intrest at the end of financial year so please win the confidance of people in your post office bank system