Only fix one thing for mac repair

So basically I’ve sent my Macbook Pro 2019 for repair for its broken keyboard (for free under butterfly keyboard thing) but then they detected tiny amounts of liquid damage and want to do a 650 dollar repair!!! I talked to 1 person on the phone today and they said it’s store policy to fix everything or return it, but does anyone know if there is any way I could convince them to only fix the keyboard.

I’m a student and there’s absolutely no way I can remotely pay for that - any suggestions would be greatly appreciated.