The IO is correct. The period between those dates is exactly 180 days. (Remember the entry date counts as day one.) Use a duration calendar to calculate.
If I read the OP correctly, it looks like this is a regular occurence. Would the new DTV be an option (assuming the cost and financial requirement aren't an issue)?
The 200 baht charge at the airport is only if you don’t have your paperwork and photos ready. Bring filled out paperwork and photos and the 200 baht charge doesn’t apply.
Fairly straight forward and quick. Have all the docs and a large stamped envelope for them to mail your passport back unless you plan to return to pick it up in person. (Takes a few days)
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