I'm "decent" now but considering the fact I grew up fairly poor and had to fight my way to the top... $3,500 is quite a bit of money.
Honestly if it were me I'd be pursuing any avenue of action I could, if you didn't sign an NDA then now is the time to start talking, I'd do enough talking to earn $3,500 that's for sure, social media is awesome hint hint.
How someone can assume they are simply keeping the money for time spent is beyond me... sure we've all had that one seemingly insane client but even then we have no right you simply refund and go about your business, this should have been the case with you they should have refunded your money or in the least considering time spent on the project refunded at least I repeat at least 85-90% of it if not all.
^ The thing is, years ago working for a company I would have said full refund, now owning my own and knowing time involved in modifications I can see how they may assume it's ok to keep the money but ALL of it? No sir some type of refund is certainly due, that's APPARENT imo and keeping it all would be wrong plain and simple.
I grew poor. I'm talking dirt poor. As a child, I was the kid who's sneakers looked more like sandles, with my toes sticking out of them. I worried about things most people I know, didn't even think about & maybe never will.
I'm far better off today, but I still have that mind set. There is part of me that will always see the value of a dollar as greater than its true worth.
So when I spend money online or anywhere, but mostly online because its a digital goods or services which I can't phsyically hold or touch. And so a part of me still feels as though I'm getting nothing, even when I do get something....
$1 = $1,000 In my head.
I've got that strong mind set that every penny needs to be held onto and saved or justified.
Even though today, I can obviously afford to do the things that I do.
I still am very thifty on most things. I have taken my history and learn from it and so I know how to manage well. For example, I've learned how to get phone service for $50 for the whole year, thus not needing to pay a monthly bill. Just because I have that mind set.
The developer who has scammed me.... He's going to get his. Trust me on this.