That was announced yesterday, but you have to wait until the decision is published in the Royal Gazette for it to become official. Although it's generally just a rubber stamp formality
I don't know if you're aware how an ED visa works. You sign up with a school for a specific course (Thai language, Muay Thai are two popular options), and the school then either organises your visa, or provides you with the relevant documents. You don't join a school and then skip from one course to another.
It looks like you entered on 10 March, which means you are already on overstay. If that's the case you need to go to immigration immediately, get the extension if they will allow it, and pay the overstay fine