IMHO:
>>>>” I do not feel like having my work, which was a product of my training and in which I take pride, changed from what would be considered good graphic design by my instructors to a nonprofessional mess by these people.”
Wrong attitude for a professional. It’s not a work of art with your name on it. It’s not a copyrighted piece that you own the rights to. They bought it, they can do what they want with it.
As for giving them the file:
You’ve already delivered what you were paid for.
Something more delivered would cost additional. What he’s looking for is to save money having someone else re-doing it or making changes.
Put a price on the file equal to what you would happy to sell it for and let the client decide if it’s worth it to buy the file or hire someone else to reproduce it.
“Wrong attitude for a professional. It’s not a work of art with your name on it. It’s not a copyrighted piece that you own the rights to. They bought it, they can do what they want with it.”
You’d be wrong about that. Payment does not confer transfer of ownership. Those without knowledge of intellectual property law commonly make that mistake.