Ruined my ITC record

I have a business bank account with Standard bank which i opened in 2012, I opened a franchise in 2014 June and started trading, before acquiring the franchise I was offered a R10000.00 overdraft, which I gladly took. As the business started growing, I went back to the bank to ask for a an increase in my overdraft and the bank refused. I had acquired a speed point machine/merchant device and my funds where delaying to clear in my business account. In short, I am very disappointed in Standard bank business division for failing to assist me in increasing my overdraft so that I can manage my business overheads. I personally think its also a color thing, I am turning over + R50000.00 and I am not getting any help from them. My record is now tarnished due to lack of business support. I have went to different branches and I had no joy.