Nedbank

Nedbank has did it again now I’m on a minus of R809.90, of what exactly I don’t know! Yesterday I had money in my account I bought groceries for R653 of which it went off today I’m logging in I’m on a minus of R809.90. Mind you they didn’t refund me the R1200 they took from my account now it’s this! Can someone please tell where can I go to sue them! Honestly this is some bull**** and I want my money!