Been threatened by FNB SA for no Reason

Hi Everyone,my name is Mr MT Kgwele I do have a business account with First national Bank,My company is not working, there is no business but im always makes sure that I put R100 to R150 in to that account so that it ca always be active Here's the problem,I received an email from FNB that says they handed me over to their lawyers So my question is,do I owe them or what ? Why can't they close that account if It doesn't work for them ? How can they handed me over to their lawyers because I don't owe them anything

Please guy's help me to get out of this problem

Kind regards,Mtkgwele