Since the Visa for Bahrain allows you to stay in Bahrain for only 2 weeks, you can now get an extension for another 2 weeks by visiting NPRA in Bahrain. (Some nationalities can stay longer).
Who is the NPRA?
The General Directorate of Nationality, Passports & Residence (NPRA) is the authority responsible for managing the entry of people to Bahrain. Part of this responsibility is processing and deciding applications for visas and eVisas for travel to Bahrain.
Telephone No: 17399764
Location in Bahrain:
Headquarter of Nationality, Passports & Residence at Exhibitions Road