you are suffering the consequences of the thousands who manipulate visa rules and Thailand like many countries are clamping down hence people crossing the English Channel from your country to find refuge in the UK in rubber dinghies - world is a screwed up place hope you find a solution to spend time with your kid, too many have been abandoned here….
Patience Nick, it’s a developing country so bureaucracy is everywhere, visas, driving license, vehicle registration etc etc nothing insurmountable with a little patience . Sadly bureaucracy leads to corrupt practices, and you will find plenty of advice about agents who will help you , for a few shekels skirt round this, but many have fallen foul of this and in some cases been deported……if you are here with family, dependents changes everything in terms of impact if you make the wrong call - 7 years here and 20 in Africa, have been a learning curve about the dangers of shortcuts…….horses for courses at the end of the day.
It’s all on your local embassy website, if you have the B 800k you are halfway there, avoid agents and corruption as and when that gravy train hits the buffers many will get hurt if not before, I do 65k a month and my renewal costs me b1900 every year very hard to escape agents clutches if you want to normalize, down the road.
It’s done in a different province to the one in which you live, many Phuket residents who use an agent get their visas issued in Pattaya - so they have to hand their passport over to a third party for their 90 day - if you try to renew anywhere else other than Pattaya (or wherever agent obtains the visa) you will be denied - and sent to that province - stuck in a hamster wheel effectively but everyone to their own.I know many folks who take this route fine until something goes wrong as it occasionally does.
After first year of maintaining 800k , and leaving it for 3 months in second year you can switch to the 65k a month for the second year - once you go with an agent very difficult to extricate yourself in future years , especially if they put up the money not to mention the risk as it’s not legal.