I found it easier to apply for 60 days by post to the Thai embassy in London. And this also meant not having to watch the calendar before 30 days expire, nor the hassle of collecting documents and travelling to immigration.
You could be right. I've just checked the Embassy website in Colombo, and there is a checklist as long as your arm. Wanting evidence of everything and you may have to attend an interview. It is obviously designed for Sri Lankans.
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