I have been applying for Non-o volunteer visas in Penang, Malaysia, for the last 2 years. Even though they mention a letter from a government agency in their requirements, they never asked for it. However, they always asked for a work permit after the first volunteer visa was obtained. My understanding is, for private NGOs, you cannot get a corresponding letter as government agencies do not oversee private NGO's. So 1-year extensions are only available for government NGO's now. And the only possibility is to get 3 month visas from abroad continuously. (This happened because the volunteer visa was widely abused). Hope it helps 🙂