Not safe anymore if anyone can just access our accounts now

I have received the worst service so far . How can money leave my ac**** and a whole bank as big as FNB just tell me there is no record of where the money went . I made a withdrawal at a nedbank ATM since it was the closest and felt safe as it was close to the branch , 1st attempt money did not come out and i went inside to ask and they said i have to go to fnb and they will file some paper , i went and filed and 2 days letter monry was back into my account . A few hours letter the money leaves my account and it’s referenced as an EFT hiw come when i never made one , i go back to the branch and do not receive any help they tell me to wait . I have been waiting for more than a month and still nothing . I received a text a few days back saying the money will be credited into my account and some lady called me , i ask when and she says since its from nedbank it will take a few days , its been days now and nothing . Have visited the branch a lot of times to get answers and see if my account is even safe and still nothing. I have texts and they even had to call me after i made a complaint at their branch only to be told my money will be back into my account in 2 days , its been a month now and still they are just giving me nothing