Well that was an experience! Got to the Immigration Office around midday today, got out of there 4 hours later! I would suggest getting there early - unlike me.
The front entrance was locked so I had to go to the right and enter through a sort of indoor market. It's signposted well until you get in there. you need to go up to the third floor and enter the office to your left. It was packed with people and with no air conditioning I would recommend taking a snack and something to drink.
When you walk through the doors, on your left is where you get the extension application form, ask the man at the desk. Then turn round and you will see an area where you can fill the form in. Don't forget that you will need a passport photo, this needs to be stuck on the top right of the form. There are little pots of glue for you to stick your finger in and attach it.
Once you have completed the form go to any of the offices that are numbered 1-4, they are on the other side of the room where all the seats are. Go in, your form and passport are checked along with your outgoing flight, I just showed the confirmation on my phone. You then get a ticket...
Depending on how busy it is you can then take a seat and go through many mixed emotions, dreaming of life outside in the fresh air, wondering the meaning of life... When your number is called you go to counter 5, it's straight in front of you when you are seated. There you collect your form and passport, look at it and wonder why it has not been stamped.
You then need to go to the payments desk 7, it's where you filled your form in. give him your form and passport, which he will keep, and pay him the 7,400srp and get a receipt in return. You can then go and relax on the chairs again with anticipation much like playing Bingo, waiting for your number to come up. Eventually you will have the winning number and you can jump up and shout BINGO and go back to desk 5 and receive your treasured passport with a lovely stamp in it.
Have fun...
Ivan