My Toyota 2017 Sienna was in an accident and damaged on the right passenger side. Our car was going 30 and a car came out of a lot and hit us in a...

My Toyota 2017 Sienna was in an accident and damaged on the right passenger side. Our car was going 30 and a car came out of a lot and hit us in a T-bone fashion and pushed into the oncoming traffic lane. All airbags deployed. Original estimate by insurance said 5k in damages. When body shop got it - it was 13k in damages and took them 3 weeks total time to repair. Insurance covered all. When I picked up at body shop, the owner asked if we had a loud whurring sound coming from the back before this accident. We did not have any sounds from the car. He said when I drive it, I'm going to notice it and when I drove off, it was definately a loud noise that never existed and I drove straight to my Toyota dealer. As soon as they drove it, they suspected the rear differntial. An hour later they diagnosed it as the coupler on the rear differential and a 2300 repair. Here's the question. The Toyota dealership is unwilling to put in writing that the accident could be a potential cause of this failure. Since they didnt drive the car beforehand and because the impact was on the side, they aren't willing to do that and my insurance refuses to pay for this additional damage without any documentation that this is a possibility. The car was towed 2 times, one to the insurance yard and then to my body shop. I'm not sure how much the body shop drove it, but they drove it to find out this was a sound they needed to disclose. Isn't it plausible that either the damage could have been caused by the initial impact or possibly during the towing process or even if the body shop drove it when the components were damaged and lubricant may have been out of the system and then this noise started. We can attest that the sound was not there before. Unfortunately my insurance has put it on us to prove otherwise. Help

Relly, thank you for your response and insight into my situation.  I am in central time in the US.   Thank you for providing me with your opinion.  My Insurance company has put the onus on me to provide documentation from sources that say that the accident could have caused this significant damage.  I'll share with them your opinion and hope that it will help me.   As of now, I'm stuck with a vehicle I can't drive and can't afford to fix.  Just one more thing 2020 has put upon many of us.  Robert

I already accepted the answer and my card was charged $17 on Dec. 17th.  also my insurance company still denied my claim so I'm out of luck.