Passport error 30-day visa instead of a 90-day?

Q: I have obtained a Non Immigrant B visa from the Thai embassy in Kuala Lumpur. When I got to Thailand, my passport was stamped a 30-day visa instead of a 90-day visa. What should I do to correct this mistake?

You more or less forgot to write your visa number at your arrival card or your visa must have been stamped somewhere else so the officer didn’t see it. It’s fine staying in Thailand with your 30 day visa as long as you don’t have to work and apply a work permit. However, if you need the Non B visa to facilitate other legal matters then you either go out of the country or visit the consular division at the immigration office for the correction of your visa.