We can definitely get you on the path to replacing the crankset, but to be completely honest, the RaceFace Ride crankset, the one that came on the bike, is a fantastic crankset for the pricepoint and you’ll find near 5 star reviews anywhere you look at it. Changing it out on your dime wouldn’t be a smart way to spend your money on the bike.
Although I can sense your frustration at the situation, the fact is you should not be spending money and time to compensate for the shop’s incompetence and apathy. You bought a brand new bike from them and that comes with a manufacturer’s warranty that will be handled by any bike shop in the world that sells Trek. If you feel you can’t get a resolution from that bike shop, see if you can find another Trek dealer in the area. If it was me, I’d have my fat ass back in that shop before you can say "bacon" and would be walking out with a repaired bike and an upgraded wheelset, carbon bars or tubeless kit for my troubles.