You need to get your own geotechnical engineer to evaluate and advise.
Agree (though I still think you need to first ask the PB to pay for that). You should be using the structural angle with the PB, not the cosmetic angle. The PB (or you) need to prove definitively what is the cause of the crack and what needs to be the fix. You two can hash out what the finish should look like once that is done.
I'm not saying this is their tactic, we want to give the PB the benefit of the doubt. But regardless of the motive, them asking you to wait until Spring to reevaluate the repair is exactly what I warned you about. If they get past the statute of limitations, and/or the warranty period, with cosmetic-only repairs, then they could be free and clear of the structural repairs.
I think
@JamesW would back up this theory: a five foot crack doesn't just happen in a 2-1/2 year old pebble finish without some underlying structural failure/defect. And so far the PB has only applied the fix for the pebble. Which is the reason I planted the seed of suspicion about the PB's behavior, and offered the tips about the evidence gathering, because he should (and very likely does) know that perfectly well. Unless you press, he'll continue to do the least possible, for as long as possible, hoping the problem won't get any worse while he is liable for it.
Again, this is based on what I just learned during my recent bout: if the crack revealed itself
after the PB's warranty expired, but
before 10 years from the date of the final inspection, that would be considered a latent defect, because the structural defect was hidden from your view. The PB would be liable for the fix. But because the crack has shown up now, in plain sight, you might not get 10 years to wait to see how bad it's going to get. It might be as little as three (I'm not certain of the deadline, that's what lawyers are for).
This popped up in a google search. It's pretty old, and the law might have changed. But read this and you'll understand why I'm hounding you to find out about the timing:
Senate Bill 800 (effective January 1, 2003); Civil Code §§ 43.99, 895-945.5 This is the third in a continuing series of Design Professionals’ Practice Updates about Senate Bill 800 (SB800) and its potential impact on the design and construction industry. Senate Bill 800 changed the statute of...
www.longlevit.com
Be sure to get to the last section: "Application of the Statutes." The very last sentence of the article is arguably the most important.