I extended mine a few weeks ago, at a Bureau of Immigration, didn't take any longer than 30 mins. Guess it depends where you are, or how busy they are?
You need a photocopy of your passport, which I didn't have, so was sent upstairs to get it done. Cost me a few pesos.
It cost me 5000 something pesos to extend my visa, so it's going to be quite pricey, for a couple of days.
May just be worth pointing out, the office we went to, they were quite stringent on dress code...No sandals or T-shirts etc....Whether they actually implement it, I don't know, so better to be safe than sorry.
