Loan charges on account accumulating weekly

Have a problem hope someone at FNB can possibly help me because at moment nobody there seems to be able to help me. I have a loan with Fnb, my credit life insurance for the loan is awaiting approval because I've been retrenched. Problem I'm having is my debit order for the loan runs on a weekly basis and because there no money in the account it bounces back and I'm being charged R110 per week. I've contacted them via app spoken to there bankers on numerous occasions but Dr order continues to run thus racking up charges. I'm hoping someone from Fnb can clarify charging me R440 for the month on charges for a R1000 d. Order please