Contact trusted visa run agencies who can assist and mediate between you and the immigration officer,
I remembered the last time i was in my visa run, There is one American has 3 months overstay ,He just pay at the border of Mukdahan (no idea how much). He depart Thailand with out overstay stamped on his passport and freely applied 2 months visa inside Savanakhet at the Thai embassy.
sorry to not stated above that i went to immigration Chaengwattana last Monday but there's a problem with the documents from the school and needed to edit. Immigration officer told me if I'm failure to comeback the day after ,I need to ask letter from the embassy to request for visa extension but unfortunately ,The embassy cant provide so it happen last minute today😢