The process is not difficult. You should be able to do it without hiring a third party. As "Leeds forever" says, just go onto the website and get the information: "https://thaievisa.go.th/non-immigrant-o". I came over on the Type O visa. My Thai wife and I went to the local immigration office in our area before my 90 days were up and talked to an immigration officer just to ask questions related to converting to a one year retirement visa. That was probably not necessary as the website is clear on the requirements. We just wanted to make sure that we did not overlook anything. He spent a lot of time with us and listed out all of the requirements. Again, that was probably not necessary but it did give us peace of mind.
-@rzugnoni
You did not convert your visa to a 1 year retirement visa. You extended your stay 1 year. You don't have a visa when in country, you're on a permission of stay.
-@Leeds forever!
Thank you for correcting my error.
Randy