How long must you be bad to be good?

I have banked with Capitec bank for several years. Like all other previously cash strapped people I have a savings account. My money goes in and out like a responsible citizen. Yes, I did get into financial trouble and yes I am trying to be a good citizen. Recently I asked for a small overdraft and was told I did not meet their criteria. I can understand that perhaps they are nervous but as they are the first people to see my money month on month what do they have to be nervous about? As things get pricier everyone is battling - even those who misstepped in the past. I am not looking for a huge amount - all i am saying is give me a small piece of trust and I will show you that I am trustworthy. Is it not better for them with all their ads for instant credit up to...(T&C's ) apply to get the money rather than wonga or someone else. They hide behind the national credit act but if someone else is quite happy to do it and is governed by the same law. If I don't meet their criteria why did they happily open an account and the answer is to take away some of my money. They want my cash but they obviously don't want me