I read all of the posts, but I don't recall seeing the ctop material. Anyway describe "warped". If indeed it is twisted or even out of level, it's not to industry standard. On top of the bbb, find out the manufacturer of the ctop material (plastic laminate or solid surface) and call them as well. For most big name solid surface, contractors have to be certified, the p-lam guys may be interested as well. Make sure to throw their name aroud.
I can't emphasize this enough. If you're asking if you're being too picky, first ask yourself this. Was it in the original agreement? If it was, under no circumstance should you accept the job. Tell them to shove the (wrong) backsplash up their rear-ends! The big box stores and their subs give you the run-around, but tell them to kick sand. It's a technique they've developed.
A real craftsman wouldn't consider taking your money until they were sure that you were happy. I may be old school, but those are my firm beliefs. I always make sure the homeowner is happy before I think about closing out an invoice. I care about my customers, they send me work. This poo-head has a big box sending him work, why should he care about his customers?
long story short, you paid someone to do something they didn't do. that should answer all of your questions.