You can refuse to pay their claim and fight it: to have a chance of prevailing, however, you'd have to show, with expert testimony (e.g. some safety expert; a mechanic who works on motor homes; a motor home dealer; etc.) one or both of the following:1) There was no need to total it--it could have been repaired safely for less than the totalled value; and/or2) Even if it was correct to total the motor home, its then-current fair  market value (which is what the value of totalling it) was less than $45,000.Of course, even you can do 1) or 2), that will reduce what they can recover, but not eliminate all liability.The only way you might be able to eliminate all liability would be if you could show that your son had no history of seizures, had not had or been aware of any medical conditions that could cause a seizure; was not taking any medicine or drugs which could cause a seizure; etc. If you can show the seizure came "out of the blue" without any warning or reason to be wary whatsoever, then you may be able to show that he was not negligent, or careless, and thus not at fault--he'd have no reasons to take any precautions (such as not driving) if he had no reason to even suspect he might seize. You'd need a medical expert for this, which could be expensive. If there was any warning or risk signs for a seizure, then your son would most likely be liable.