The immigration office in Dumaguete is a lot more relaxed than the Manila counterpart. Expenstions are easy and take a few minutes as opposed to a whole day in Intramouros.
The Dumaguete Immigration Office is located at ACO Door number eight, Lu Pega Building 38 Dr V Locsin Street.
Their phone number is : 035 225 4401
So if you need extensions or other immigration issues handled I would strongly suggest you try the local Dumaguete Immigration Office before venturing in to Manila to face the struggles of main office.