Kotak Mahindra Bank — Deduction of amount without information

Address: Karwan, Hyderabad

Greetings of the day!!!
I have bank account with kotak mahindra since 2017 and it was salaried account but in august 2018 i left my job but bank account was active and suddenly without information bank deducted 2670+ rupees from my account on 13 of october 2019 sunday when enquired about they said as it is salary account i need to maintain some minimum amount in bank that is why they charged me and asked me to convert my account with savings so i will not be charged again even if i don't maintain any balance because it would be zero maintenance account so i gave them written letter to change my account from salaried to savings and they did, but now today again they deducted 1112 rupees without informing me when i checked in bank's app it is written for not maintaining minimum amount even though i am keeping some amount in that, kindly help me this is 3rd time i am facing money deduction issues from this bank.
Thanks & regards.
Mohammed zameer ahmed