The multiple entry option for Non O is removed in the e-visa system. You can apply for the one year extension of stay in Thailand and purchase multiple re-entry permits.
The page I posted still describes the formal requirements for applying for Non O e-visa through the Thai Embassy of London. For applying for the e-visa you use the site Brandon provided.
Previously you only were entitled to a 15 days Visa on Arrival at the airport at 2000 baht. Since July 15 last year you’re moved to the 60 days visa exemption list together with 92 other nations.
Previously you only got a 15 days visa exemption if you entered by land or sea, but that’s back to before 2016. (30 days by air, but now 60 days at any entry points).
If you only got 15 days at an airport you could be among citizen only allowed to a 15 days Visa on Arrival who now since July 15 last year are entitled to a 60 days visa exemption.
This was after the crackdown and agent couldn’t open anymore. I was denied in three branches in Pattaya (Bangkok Bank and Krungthai) with a Non O visa and allowed in this BB on Jomtien.