I used Siam Legal as well, back in 2015 and had no problems with them at all. Was in BKK when first arriving to retire here. So had to start at CW with Siam Legal helping all the way to the point of assisting me to get a bank account set up. Then we were moving to the place where our home was going to be built which was in Prachuap Khiri Khan province. The lad came down to Hua Hin Immigration to do the final part so I could then do 90 day reports in the province.
They also did, my then girlfriend and now wife's, visa for a visit to UK. When it was refused first time because the UK powers never read the documents fully, the girl at Siam Legal did the new application for no extra costs as she was not happy with the refusal. After a strongly worded application was made again, the visa was granted.
So, I have nothing but praise for Siam Legal and will be using them in the future when we need another visa for the wife so we can visit UK for a holiday.