Get your taxes done using TurboTax

Yes, I understand this, but I didn't request an extension to FILE my taxes, I requested a short-term extension to pay my taxes. I know there will be penalties / interest acrued since I am deliquent as of a few days ago. I had gone online to the pay your taxes section and requested the short term extension to pay by August, and it was auto-approved. However, my question is if it is possible some someone to convert the short term payment extension (6 months) into a longer term (ie. 12 month)? Or if it's basically set in stone. I have accepted this will cost me in interest and used a calculator to calculate what it will cost me in the end.