So I went to immigration yesterday with all paperwork.
I started by giving her my passport and TM47. After 2 minutes she gave me the passport back along with the new 90 days notification date receipt.
She said, that's done, you're good to go. She didn't even look at the fact the TM47 I gave to her hadn't been signed yet, and it didn't have a date on it, so I told her so and I did sign it and left, thanks
you'll go to any immigration office while in Thailand, 10 days before your exemption stamp (30 days) expires, and you get there an extension (additional 30 days) at a price of 1900 baht