Express Oil Change complaint: Undercarriage fell off

I got an oil change on 7/8/23. On 8/2/23 @ approximately 6:20 AM as I was leaving work my undercarriage cover became unsecured from the bottom of my car. I commute over an 1 1/5 one way. I called the place of business to speaker to a manager when they opened and explained to him what happened. He told me to bring it in. I did bring my car down. He came out and looked at it and told me to pull over to the stall so he could get under the car. He tried to explain to me that they don’t have to remove that part when they change the oil, when I know they have to. I have had to wait after my oils change was completed just so they could put the undercarriage back on. He then tried to make out as if I had hit something. Very unprofessional when a customer has the complaint. I asked for his manager and the number. He basically told me his name was Shaun and it’s the same number I called before. Again, very unprofessional. It may not matter to the owner, but I will never patronize this business again for the way my complaint was handled.