Bank Of India — after transaction, i'm not getting actual balance

Before transaction my a/c balance is 13147.42 on 6 nov.5:01pm. I withdrawn by atm rs 2000 then i got the balance is 11147.42 again i withdrawn rs.3000 same date & 5:05 pm by atm now my balance was rs.2147.42 but it should be rs.8147.42. Kindly provide the information of 6000 according to actual transaction.
Such type of cases, who is responsible?
I have also contact bank of india executive he told me i withdrawn rs.6000 but i'm saying i didn't, the big proof is cc camera is there. I only withdrawn partially 2000 and3000 between these transactions who withdrawn rs.6000. I don't know. What is the process to get my money as soon as possible plz provide me.
Nobody paid the attention for such type of cases even bank of india executive.
‌plz register my complain otherwise i'll go head office mumbai.