Don't know how AU limit increase works. They told me to send an email with latest 3 months pay slip and a statement to allow them cibil check. Later they closed it without even checking my Cibil and considering my payslip.
After calling them, they told that I don't have offer. Those people don't even realise why should I email them if I already has an offer for credit limit increase.
I never got an increase since taking the card about 2 years ago. Utilisation is between 10 - 70% (avg 25%) through out.. every month. As it is my 1st preferred card (AU Lit).