Butterfly keyboard repair

I had a sticky key on a MacBook Pro - 2017 model. I tried to lift the key to see if there was debris underneath. Unfortunately, the white plastic butterfly mechanism came off with the key cover. I took it to the Apple store and was told that the only way to repair it was to send it in and have the whole keyboard replaced - for $500! I asked about the keyboard replacement program since sticky keys were a known problem with the design. I was told I voided my warranty by trying to pull the key up. I was so furious that I walked out of the store. Does anyone have any advice on alternatives? I can’t believe a company like Apple would design a product where a single key on the keyboard requires a $500 fix. The support at the store was also rude and not helpful.

Thanks in advance.