Changwattana road borders Muang Thong Thani. There are two immigration offices within a few km of each other? Pak Si is where immigration is located on the south side of Changwattana road, Muang Thong Thani is on the other side a km or two west of immigration.
He's in beantown so I think he's styled. I'll pass along the suggestion. He hasn't been here at all in 2018 after all so it shouldn't be an issue but you never know.
No, it was my fourth extension. None of them took more than an hour except one time when I arrived around 11 at the Sirindhorn office and they broke for lunch but I was still in and out in under 2