AM Used Auto Parts [AMUAP] review: Used engine

A used engine was purchased by our customer and sent to us to install. It leaked internally and needed to be replaced. Because the the date of pickup was after the thirty days, as the customer had to gather up funds to pay the bill, they denied the claim. I had mistakenly gave the date of the pickup as the date of the install, which was after the thirty days. I explained to them that the motor was installed the following week after delivery but that the customer was unable to pickup until they had gotten the funds together. They said that I could not change any information and the claim was already denied. I explained that there was no way that the engine could have been installed that same day that the customer paid and picked up which would prove my point. They would not give me any other information as to who I could talk to and started talking in circles, just kept repeating what he had said -(name:Daniel Johnson). He would not give the name of a supervisor or owner that I could talk to and no other information other than his number. The cusotmer had not even driven the vehicle enough to require an oil change.