fnb debt collectors

Last month I was contacted by a debt collecting agency that fnb had sent. I was contacted by a person called Edmund Abrahams. I was behind on my fnb loan as a result of losing hours at my job. This person took r6753, 87k which I was in arrears with from my account without me even signing any forms and left me without food or money for transport to go to work the whole month as I only earn r8500 a month. I spoke to him saying I can't afford that amount every month because it leaves me without food, transport and no means to meet other financial obligations. He agreed on r2000 and I have the emails to prove it but they still took 6753,84 from my account today. How does Fnb expect one to live after this? Prior to this I was paying r2000 for my loan, how can I default on r2000 but have the affordability to pay r6753,84?is this how fnb treats its clients? Where did Edmund get my signature if I didn't sign the form? These are ******* tactics that this person is using. I have never refused to pay fnb and do want to pay but I can't afford this. Fnb please deal with this matter asap