State Bank Of India [SBI] — Cash deposit charges?

Address: Nagpur, Maharashtra, 440022

I deposited Rs. 1.50 lakhs in my own account in the same "home" branch and this is my first cash deposit transaction of the month. I have been charged Rs. 51.75 and the description for the same is "Cash Handling Charges". I thought 3 cash deposits per month were free. So I contacted the SBI customer care and the only thing they tell me is to contact the branch but whatever action has been taken is correct. I do not see any rule book which says they can charge me this money but it seems in SBI wonderland, they can make up the rules as they want. What a weird institution to transact your business with :( How do I get my Rs. 51.75 back now?