If I understand your post correctly, then sadly for me, Phuket immigration didn’t follow that guideline. And in so doing, denied me an extra two months...
My extension of stay was granted on 28 August (after being under consideration from 29 July) and was stamped with an extension of stay only until 29 July 21.
given you were rejected at DMK, it would be best to tell why that was and provide an overview of your visit and visa history in order to get clear advice...