In the uk I apply online at the Thai embassy for a 60 day tourist visa, then in Thailand 10 days before 60 day visa finishes I apply for a 30 day visa extension at the local immigration center about 1900 baht
Yes I’ve just done that 60days the old way visa in the uk, then 30 days immigration Blueport, then five days in Vietnam with another 60 days on return to Thailand
I apply for a 60 visa in the uk then a 30 day extension at Hua hin immigration I have a return flight booked usually within 90 days never had a problem