fellow Saffa here. Please note you now have to do your initial application in South Africa at VFS Global or BLS (the latter "lost" my application and then sent my passport to another office so I would recommend VFS). The locations are listed on the Royal Thai Embassy site, and you can make an appointment 🤗
For Chiang Mai, you need to report your return within 24 hours, landlord not needed. Normally they will put another stamp (or scrawled note) on your previous TM30 slip
Sorry for creating confusion. You will NOT need a matric certificate for your marriage visa. James summed up what you need to do above.
First step is to contact the Thai embassy by phone - everybody speaks excellent English. I would also take a photo of the marriage certificate and send it to the embassy.
It sounds like they will want a certified copy, in which case you will need to send it to Dirco in South Africa - this might take a while. I used an agent to get my docs certified. I can PM you their name if you would like.
But first step is to talk to the people at the Thai embassy in Pretoria: 012 342 5470
1. Phone the Thai embassy in Pretoria, I found them very, very helpful. I am sure they can assist you with advice as to how to get the marriage certificate re-issued with the Thai ID number. And I would absolutely recommend you get this done while in SA.
2. On the Thai side, things are getting very strict. Thai immigration is asking for more documents than they ever have (eg. I had to provide my matric certificate from 35 years ago, even though I've lived in Thailand for 20 plus years). I would say this is especially so for those of us from Africa. I have had to provide many more documents than I ever had to before.
3. It took 3 months for me to get the required certificate in point 2 from SA. And the Thai immigration officers had zero empathy for delays due to Covid...
4. I strongly suggest you get every single document that may possibly be needed certified while you are still in South Africa. DO NOT come to Thailand on a Tourist visa and hope a transition will be easy. It has never been easy for those of us from Africa, and its much harder now than it was before. (I know getting things sorted out seems like a big hassle in South Africa, but trust me, its MUCH more of a hassle trying to get things done when you are in Thailand). Sort out everything in South Africa before you come here.
5. I understand that other posters are trying to help, but there is a huge difference between being from "Africa" and being from the USA when it comes to Thai immigration.
* I'm going to mention again, the staff at the Thai embassy in Pretoria are fantastic humans. Contact them, and follow what they say. All the best