Service techs broke my computer

I've only had my dell inspiron for 3 months when a single key broke off, no big deal I tried finding it to replace online but they would only do the entire keyboard. I figured instead of buying it myself and doing it I would just have them do it for free since it's still covered under warranty. 

Anyways the tech comes, and by the time he leaves my fan/motherboard had issues. All because I wanted a single key replaced. So they send out a second service tech, and he didn't fix it. 

At this point they're offering to send out another service tech but I think everyone can understand why I wouldn't want to deal with that a third time? They're refusing to replace my brand new computer because of the "age", but I think it's more concerning that it's so new and now is having all of these issues thanks to one of their service techs. 

I just want it replaced, I don't want to deal wi