Bad Unfair

I was recently informed that i can apply for a limit increase which i did, i was offered a limit increase subject to sending bank statements, which i did, my income is R 2550 plus R 1700 which i receive from my son each month, i did declare that on the application as requested, today i receive a notification it has been declined. I have never missed a payment on this account neither on any of my other accounts, as far as i know my account is in good standing, never once miss used it, why am i treated like this ? I have been a loyal customer, always paying and even more than what my payment should be, i find this absolutely unfair and horrible, trwatment !