Im sorry that you feel that you were charged diagnosis for a complaint that you broght your vehicle in for, We installed your brake controller on 6/6/25 and you brought it back on 7/21/25 with the complant that the trailer brake controller that you brought in and had us install only worked only if you manually use the brake controller. As i explained to you over the phone we inspected the work we did and everything was fine. We also hooked it up to a trailer to verify that the brake controller that you supplied was not bad. We then proceded to diagnosis the problem. We found that brake switch is bad which we had told you was bad when we had your tahoe in and diagnosed your oil pressure concern and you declined replacing it then. I would be willing to apply the $55 toward the replacement of your brake switch but only if we supply the part. We back or parts and labor up with a warranty if we install parts we supply. We always make that clear and up front when customers want us to install parts that they supply, and for that reason is why we dont install customer supplied parts except on a rare exceptions like we made for you on that trailer brake controller.
We are sorry for the inconvience this has caused you. We will be glad to go for a ride with you to better understand and diagnose this concern. Thank you for your time