UNAUTHORISED PAYMENTS

I am not happy with Capitec Bank service, there has been app called infinity accessing my online banking app and extracting money without my permission. It has taken up to R2000 now. I have went to the bank branch to ask the consultant to stop this infinity from taking money. The consultant gave me a new card and said she stopped the app from accessing my account, to my surprise today the same app took R600. Capitec please assist I don't understand how an app can access my bank account without my permission. I do not remember approving such an app from taking my money.