I think the biggest problem that has come to light here is that you have absolutely zero patience. If you require 24 hour payment, which is already not the eBay standard but whatever, not the point, then give the buyer 24 HOURS to pay for the damn thing without having to respond to 15 messages.
That being said, yes NPB's suck but that's part of eBay. No use complaining about it here unless you are giving out names for others to block.
Nordy 20 Caser: Hunter Renfroe, Jorge Soler SCB 10 case: Jon Denney, Danny Salazar, Scooter Gennett, Aaron Sanchez, Johnny Hellweg H/D 50 caser: High Risk Case 20 (D), Corey Seager (D), Sonny Gray (HD), Johnny Hellweg (H) 36 case Auction: Hunter Renfroe 34 Case Auction: Jon Denney