What should I do if I need a visa extension before the amnesty expiration on September 26th?

There is no "appeals for leniency" :O

If you haven't sorted out a long term extension by now, you either have the embassy letter and you get a 30 day extension OR you have a letter from a doctor or hospital to get a medical extension OR you prepare to depart on or by the 26th of Sept..

They are telling people to apply now because there is no up side to waiting until the last day because the amnesty specifically states the extension will start on the 27th of Sept.