You go early morning at 6.15am to typing center near immigration and take visa extension application from typing center.
Then take signature from captain in immigration office at first floor (once you enter the gate first building). Once you got signature submit your application + tickets there itself for entering their system.
After that you will go visa counter.
Also ask somebody inside immigration office many people can help you.
I did same……. I got 1 month visa extension after 6 month.