Unauthorized debit orders

I'm thinking of changing banks and closing my cheque account, every single week a new debit order debits me account, not certain why and how they letting them through. They even sending me smss's about me know about the debit order yet it's gone through. They range from R99' R126, R397 this is a lot of money that goes out. I'm getting tired of reversing and putting stop payments on them. It's really frustrating maybe moving to another banking Will be better