Please refund my money

Hi Fnb,I mistakenly transferred R8000 instead of R800 into my overdraft account and now when I contact your guys,the advisor states it is up to Fnbs discretion to decide to refund the money ,please could you atleast refund R7000 back,I am aware I am behind in payments but that was my only salary for the rest of March,and I just starting work again and will be paying my accounts diligently like how I use to, you can see my conduct over the years, it's very unfair and I don't know how I am going to cope for the rest of March,