What response did the MP get? What is the standard response that you refer to? Is it that the application is under consideration? Ask them to put the file under
active consideration (point 9 on the link).
On the positive side, if the Home office states (especially to an MP) that the application is still being considered, that means that your friend's Section 3c leave is still extant (assuming that he had it to start with).
Has your friend moved addresses? Has the Home Office ever got back to him asking for more information or proof?
I am not a lawyer or immigration advisor. My statements/comments do not constitute legal advice. E&OE. Please do not PM me for advice.