Am I justified in my frustration?

Looks like you got your money's worth and sounds like your doing everything within reason to get it apart. We've all had our share of Jackie Gleason Sav-A-Buck capers which this sounds like it may become which will add insult to injury if you've got to abandon and purchase another.

Is this a Suregrip rear and what's the 3rd member #, I think with persistence you'll get it apart but at what cost to the internal components.