State Bank Of India [SBI] — about transaction through atm

I have a saving account in state bank of india, trauwala branch, paonta sahib. On 7th sep 2019, multiple suspicious transactions has been completed against my account and debited around rs. 801+45/- with three transactions (As rs.1 first, rs.399, rs.399 about rs.45 i have no information). I have not received any otp (One time password) also to authenticate the transaction. Below is the sms which i got.

Sbidrcard x3436 used for rs399.00 on06sep19 at99999999 txn#* if not done by u fwd this sms to [protected] or call[protected] to block ur card. (Here due to security reasons i secure transaction i'd of that particular transaction)
I block my card after that.
But i need to know without sharing any otp or any important information like (Card no, cvv no, pin no) how such type of transaction is happen.
Plese tell me which type of mistake done by me so that i can prevent my self in future.
And aslo plese give me information about refund of my money.