@Craig ********
it's that extension process run by VFS Global for the immigration office, the minimum "service fee" is 500 baht, plus the 1900baht extension,
You apply upload your documents, pay wait for them to approve it and tell you when you go to the 3rd floor of Building B at the government complex with all your paperwork and then they put the eExtension sticker in your passport
you go here once it's approved (its really the 3rd floor because the main immigration office is located on the 2nd floor (even though you walk right into that floor from outside ๐ฎ )