Debit check mandate,*****

I have been having problems with debicheck mandate I spoke to this people that I want to pay by hand month to month they keep debiting my account is always on minus because of this debi mandate I even told fnb agent that I want my fnb and direct axis insurance and LegalWise debi mandate should stay the same but the rest must be suspended but the agent said there is no way I must speak to tje service provider so I am really sorry although I love fnb I am moving my account to another bank how do I speak to people who dont want to remove the mandate and causing me 1500 monthly????because of unpaid 115 amount