I would send the letter. How is management going to know unless they hear from the customer? They may be aware of this behavior and allowing it to happen so the letter may be a wake up call. I recently had my CH in at R&R Mack in Youngstown for a switch to be added to the dash to drop the air on the trailer. Things started downhill when I was told I could not stay with the truck while it was being serviced. When my hour job turned into a three hour job and I was finished and went to leave I found greasy boot prints on the newly scrubbed carpet, my IPad was on the floor and had been stepped on, yes more greasy boot prints, and I had to take the dash apart to correctly reset the switch labels which were not aligned properly. I was furious! In a couple of days I had calmed down and received a customer follow up survey from Mack. Yes, I did fill it out and did not rate service very high. I may not be welcomed back next time but at least Mack was made aware of this inferior service. This tech has over 30 years of service and this should not have happened. The opposite of this happens at W W Williams in Hubbard, OH when I take my bus RV in for service. They immediately cover the seat with plastic and put plastic all over the floor. They won't even get inside so of it. I stay with it so they ask me to start it and drive it in and out. Why should a truck be treated any different? Go for it.