If you released it under a free software license, then all they seem to have not done properly is putting an attribution text in their software. But you did not specify what license you used which already makes me doubt if you have the correct mental model around free software and it's ethos. Who makes money on what is not the main concern in free software ideology. It's a side question. It's the four freedoms that are the main points. Then there is the question of copyleft but you didn't specify your license so I won't elaborate on that. But even that doesn't block a rebranded release for sale.