u/Deep-Lecture5412

I have a Smart Fortwo 2009. The exhaust recently started blowing. I took it to the local garage. They replaced it with a much louder exhaust. The Eco stop-start no longer works. I'm livid. I haven't paid them yet. They said it's different because it's an aftermarket part. Options.

Gemini gave this answer. I'd like some human advice too>
https://gemini.google.com/share/b137400bb6cf