I am going by the fact that I had seen in many places that anything beyond 90C for a dark roast was effectively burning the coffee and to stay between 80 and 85 ideally

The shipper may have a say in this, too. I skimmed the USPS "File a Claim" steps. It asks for proof that the receiver simply doesn't have. Unless Clive Coffee can provide a reasonable explanation why the burden of non-delivery falls on the receiver, I agree with you: Go elsewhere. That said, it's rare to hear a complaint about

Yes, trying not to touch the metal

Good points. Where are you measuring temp? Inside where it exits from the chimney? 88C seems too cool if that's where you're measuring

Great primer Tim! I had an Ethiopian cold brew at a local restaurant last summer that was splendid. It had a berry peach like tea look and taste to it. So delicious. Your post is making me reminisce