An unsatisfied angry client

A very unsatisfied client My capitec account got blocked because of money I got from an online investment I took, I gave them everything they wanted and submitted an affidavit after going back and forth with them I don't know how many times. Now my account is unblocked but money was taken out of it. I want to understand on what grounds or what right does the bank have to take money out of my account without my permission, surely that cannot be legal. I want answers and im sick and tired of being taken from pillar to post.