you visit the immigration office that you want to do the extension at, and ask for a list of requirements for a 30 day extension, if you submit all the required documents it will get approved, the only problem I've heard of people having, is if the accommodation your staying in hasn't registered a TM30.
you said 31 to 60 days requires a tourist visa, I said if arriving on a 30 day visa exempt, and then extending at your local immigration office, for a further 30 days, it is not the same thing, a 60 day tourist visa you buy in advance, and upon your arrival in Thailand you get stamped in for 60 days, and can if you so wish, extend that for a further 30 days 🤷
American passport holders can just arrive and get stamped in for 30 days visa exempt, and then visit their local immigration office and get a 30 day extension.
I have struggled a bit myself in the past with the Thai e-visa website, it's not the best, I've learnt a few tricks now tho, a relative of mine said he was having problems uploading photos to the E-visa site with his iPhone, he said he thought it would be easier because all the jpeg photos of the required documents was on his phone, but he said he couldn't achieve it, I suggested uploading the jpeg photos to his laptop, and try that, he contacted me the day after to say all done, his visa got approved at the London embassy in a few days 😅
What is the problem your having to upload the photo?? It's best to do it on a laptop if possible, just take a selfie "passport style" photo with your phone against a white background, upload any photos to the laptop, then just drag and drop the jpeg photo into the box, check the photos are not too big, or they just bounce back out, if the photo is too big, you need to crop it in a photo editor.
Select includes all taxes and fees total price, also select any discount codes and coupons they are giving you, then you should get the price you were expecting at the payment stage
I thought he could just take it as it comes, and if need be just apply for a visa on arrival, when at the immigration border in Vietnam, but it appears it needs to be sorted in advance, it should have been planned in advance not on his departure day, it looks like he would need to transfer his flight to a later date, when he has got a visa, that's if his flights are booked separately.
If it's the same booking for both flights, with the same airline on the same ticket, your hold luggage will automatically be transferred onto your connecting flight, when you check in at the start of your journey in your home country, just ask the airline check in staff if your luggage will be automatically transferred, they will confirm 100% yes or no.