i just came back from airport immigration office and they informed me that tourist visa on personal sponsorship is suspended, i want to bring my mother for 10 days visit.

i know that i need a letter from my work , this i can manage. do i have to go to immigration central office to apply for her visa or there is other office? what is the duration of visit visa? how long does it take to process the visa? what is the fees for the visit visa ? what is working hours of immigration office?