Retirement extension – inadequate funds -overstay?

A “what if” scenario, but a distinct possibility. An elderly, infirm and frequently confused friend of mine has been living in LoS for the past 15 years or so on a retirement extension without any major problems that can’t be overcome with a bit of helping the process along. As he cannot complete the progress himself, he’s previously relied on various agents acquainted with the system to obtain his retirement extension to help him outwhen his bank account was a bit low. With yet another crackdown on improper visa procedure looming due to the appointment of the new Immigration supremo, “what if” my friend leaves it until there are less than the required 3 months forthe required money to be on deposit in the bank prior to renewal, or he can’t raise it and he can’t find an agent willing to help him out as before due to a possible crackdown? If the law is strictly applied, he will be unable to renew his extension and come the due date, will become an overstayer. If he then voluntarily goes to immigration and pays his fine, can he then apply for an extension (assuming he can get the funds), or will he have to start the whole Non-Immigrant “o”/retirement visa process all over again, or will he have to leave the country? If that happens, due to his age and health, he won’t be back.
So the worst case scenario for him is not enough money in the bank with less than 3 months before his renewal application andagents unable to help withthe law beingstrictly enforced regarding overstayers. One important issue is the timing of the “3 months money in the bank” requirement. If the 3 months startsprior to the date his application is being made (usually a month or so before the extension runs out?), he will struggle to get it on deposit in time, or is it from the actual date of expiry of his extension? In which case he might have enough time to raise the money and get it in the bank.
Any helpful tips would be much appreciated.