What documents are required for a 30-day visa extension in Thailand, specifically in Pattaya and Bangkok?

This post discusses the experience of applying for a 30-day visa extension in Pattaya and subsequent documentation requirements when visiting the Bangkok immigration office. The user shares that, despite believing they had all necessary documents, additional documentation was requested in Pattaya. They detail the specific documents required for the Bangkok office, which included the visa extension application, an embassy letter, a copy of their passport, and the TM6 Thai entry/exit form, along with an overstay penalty acknowledgement form.