My money was called "Set Off" and was withdrawn

Capitec: Your savings account had a negative balance. We app**** set-off, which means R****** was debited to account ********** and R****** credited to account ********** to recover the negative balance. Info ***

Capitec what is this? I need my money, you guys never try to inform me about this you just take my money without any negotiations, I don't have money now in this crisis of covid19. I'm so disappointed with you, I need my money back.