Blind Spot Monitoring System Malfunction (3 times!!!!)

How can I resolve this issue? I bought a 2017 Prius 4 with low miles in April 2019. I didn't notice but it had a painted over scratch on the bumper where the blind spot monitoring system is. Less than 30 days later the BSM system malfunctioned and I returned it to the dealer for service. They said that I had scraped the car on the rear side panel and that made the warranty not cover the BSL damage. So I paid for the costly repair. Now, (October 2019) 5 months later, I am having the same problem and Toyota is saying that it was because I must have driven over a large bump and due to my driving, it is not covered and I have to pay again to have it fixed.

At this point, I looked up the service records and this same problem was repaired by the previous owner in April of 2017! So? Three times, this has been fixed? How can I resolve this?

 

I have not hit anything with the bumper.

 

I looked up the records. I bought the car on 4/6/19, 18 days later I brought it in because the BSM malfunctioned, they said that because of the damage, small scrape on the bumper, it was not under warranty and they charged me $341.11 and it took 5 days to repair it. Now, less than six months later, it is malfunctioning again and they again say it is not under warranty because only parts are under warranty and this is labor to re-mount it.

There probably is no record of an accident because it is just a scrape. I called the Toyota main customer service line and it seems like they are not going to help either. They say that they only cover parts not labor and it seems that the part keeps coming loose and they say it must be my driving. I have not even had a parking ticket, I am a slow safe driver. but the dealership is the one that decides what it covered and it seems that a part coming loose repeatedly is not covered.