Money hungry

I’ve informed FNB multiple times that I’m currently not working due to being retrenched a year ago and still not able to find work .I’ve made payment arrangements for my FNB products but they still try to debt my cheque account .every month I atleast have 3 or 4 unpaid magtape debits on my account of R110 each . My account is now in a minus of almost a R1000 . This becoming ridiculous,if I have no income and make arrangements to pay alittle on each account per month .why try and debit me .