Seller Won't Pay for New C of O

[Richelle Bryan]

Hi All,

My offer was accepted but the seller has a C of O (done 18 months ago) that is not transferable and will not give credit for a new one and is not negotiating. 

First off why would a C of O not be transferable? And second, is this reasonable for the seller to say this or do I walk? I have 24 hours to accept.

Richelle