Waleykum Salam,
The place I know for arranging Umrah Visa is located near Hafsa Signal. On the C ring road coming from Toyota take right from Muntaza Signal go past the small traffic signal after Apollo Clinic take left from the signal and immediately take right the agent is located on the left hand side and has a big open parking in front. They charged us 200\passport and for children under 7 they charge little less. It takes 7 to 10 days to get the visa stamped on your passport and they can also advise you for the best place to rent.