Can I extend my Visa Exempt stay in Thailand for an additional 30 days and what documentation is required?

you should have been stamped until August 19, not August 15 on a 45 day visa exempt.

> Any possibility to apply for another extension of 30 days

Yes, you can get ONE 30 day extension of stay based on tourism. You will need:

1. Your passport and:

a. a copy of your data ("picture") page

b. a copy of your most recent visa (if you have one)

c. a copy of your most recent stamp

d. a copy of your departure card

2. A TM30, filed in the immigration office.

3. The forms (each immigration office may have different forms, and ant to use their special forms)

4. 2x passport pictures

5. 1,900 THB processing fee