What visa should South Africans apply for to teach in Thailand, and can they secure a teaching position upon arrival?

Hi, I am planning on coming to Thailand from South Africa in December. I am hoping to find a teaching position- I have the relevant teaching degree's and experience as well as TEFL course.

I have just heard that they are not giving South Africans visas and we have to sort our visa out in SA before we come as it's the only embassy that will process it? (The non b visa) but I can only get this visa once I have a job right? I've heard though that you can only really secure a teaching position once you in Thailand as they want you to come in to the schools etc. I was going to come on the 30 day exemption stamp you get at the airport and in those 30 days hopefully secure a job and then sort the non b visa and work permit out while there. Now I'm hearing this and stressing a bit. Please any advice would be greatly appreciated.