NHTSA Complaint #11553117 — 2018 TESLA MODEL 3

I was parallel parking the vehicle and I heard a loud "thunk" sound. I looked under chassis and came to learn that arm connected to wheel had completely fallen off. Luckily, this was not on freeway or with my family. Vehicle was taken to Tesla for inspection, they mentioned this should NOT have happened and they couldn't explain for how this would have been undone, initially. They stated they'd replace both arms but would be fee on customer $1200+ which I was bewildered that not only is this part not supposed to easily come off but that this would be something I needed to pay for. I asked that they take this up with management, they came back 20min later to state they notice slight deterioration and sent me an image, which I could barely see and now explained this "could" have been the cause. I've had some folks share that this may be a known issue with 2018 Model 3, which is also same year my vehicle was made it. I'm really disappointed as this is our second Tesla and this has been first huge incident and luckily it wasn't with others inside, as this could have turned out very differently