that you "paid for a service for which you didn't receive" is your version of the story. i'd be willing to bet that the programmer involved would have quite a different one. i'm not making any claims about who's right or wrong, i'm just pointing out that he's likely willing to fight you over it.

suppose you reverse-engineer the app and the old programmer finds out. he says "hey, that's my work, you are not allowed to do that" and sues you. if he's as vindictive and unproductive as you claim, that seems a likely outcome.

what you're talking about is throwing good money and effort after bad. you're digging yourself into a deep, dark hole. you and the programmer could be taking revenge shots at each other for years.

starting over puts you at zero, which is way better than sinking deeper and deeper into negative numbers.