As far as I know, only a Social Budaya visa can be extended. The extension of a Tourist Visa is not possible. The VOA is yet another story of course.
It is based on this law:
[FONT=arial][COLOR=#000000]KEPUTUSAN MENTERI KEHAKIMAN REPUBLIK INDONESIA NOMOR M.02-IZ.01.10 TAHUN 1995[/COLOR]
[COLOR=#000000]TENTANG VISA SINGGAH, VISA KUNJUNGAN, VISA TINGGAL TERBATAS, IZIN MASUK, DAN IZIN KEIMIGRASIAN[/COLOR]
[COLOR=#000000](1)Izin Kunjungan dapat diperpanjang kecuali untuk Izin Kunjungan Wisata.[/COLOR]
[/FONT][/COLOR]The answers they get from other people however, include these remarks:
- This is an old law of '95 and there have been modifications and an addendum since.
- This law has been changed in 2011.
- In 2006 the SosBud and Tourist Visa both got the code 211 and so they are the same.
- An agent can convert the Tourist Visa to a SosBud while you're in RI.
Many people even declare they have extended their Tourist Visa, with or without sponsor. (E.g. in Ambon and Makassar.) If that required a sponsor that would be easy explainable of course: a mix-up by Immigration. (They thought they dealt with a SosBud.) I could not make up if they used an agent for the extension or not.
Now I realize it's always the person him/herself who gets into trouble when they have a government agency done something which isn't kosher after the facts. (It's not so obvious to point a finger and say: they said it was okay.) Therefore it's rather important to get this out of the way...