As I was assembling one of the chairs the seat split into. Not sure if I might have tighten the screws to much. How can I get a new seat

Seem very heavy duty. I have a fiend that is pushing 300lb and visits regularly, none of my chairs held up to him. These will. Very basic finish workmanship is on par with the price. If you wanted to you could sand re stain and shellac them making them look much more expensive. I am happy with my purchase. They were easy to assemble for me even the the instructions are not very detailed, you must look carefully at the drawings to make sure your orienting things the correct way. First chair took about an hour with unpacking and organizing. Second chair took about 20 min. Don't use impact tools on any bolts that go into the pressed in nuts. I only used my impact driver on the screws that go into the wood.

Very solid, assembly was simple and step by step