SBI Credit Cards — SBI Card is auto debiting huge bulk amount from my savings account without my consent.

Address:	Bangalore, Karnataka, 560017
Website:	www.sbicard.com/en/home.page

Hi SBI Credit Card auto debits bulk amount from my Savings Account (which is in SBI PBB) without my permission. i have not given approval, still they are debiting large value putting me into risk without checking with me on balance. i would have issued Post dated cheques and this act of SBI card is putting me into risky situation. This happens every month. they do not provide soft copy of statements and i do not know what and how much are the charges of the debit!! their online details are more than 2 months old which is of no use. No bill or statement comes!
Inspite of me paying minimum amount every month they go ahead and debit the value which is resulting in my money getting struck with Credit Card!! i am giving credit to SBI card! if the credit limit is 20k, they are deleted more than 22 or 25 k every month exceeding value of actual spending!
Request please help to look into this seriously as they are using my money in their credit without any charges.
once this is resolved legally i will cancel the card.