State Bank Of India [SBI] — unauthorised debit from my account

Address:

Khagaria, Bihar, 848203

On 05/07/2018 at 17:07 i get an sms from vm-cbssbi sying that-your accountxxxxx895436 has a debit by trasfer of rs.2000.00 on05/07/18.quicly i logged in sbi online to see detail there is -debit txn_reference180703/[protected]/[protected]/-only no any further detail.
thish transaction is not done by me anyway.i talked to customer service they refused to help.instead they adviced to block my one card.i gave permisson to him and they blocked.next day go to the branch bm not gave any cure.hence credit me 2000 in my account.