You just got supremely unlucky and it's okay to be frustrated at that, but it happens to a lot of folks and isn't a sign that something is inherently broken. It took me 6 years of playing this game on and off to finally get Hate to drop from Stalker. Just because something has a 22% chance to drop doesn't mean you're guaranteed to get it within 5 tries.
You also don't mention specifically which frame you were trying for there. *EDIT* Keyshare didn't tip me off to it being Mesa, it has been a long time. While it does suck trying to get her parts, you should have set your expectations with how the keys were acquired that it wasn't something you could get done quickly.