Would the passenger that your husband was dropping off not give a witness statement? And have you explained to the insurance company that there is a tow bar that would have caused damage if the accident happened in the way that the third party is claiming? If the minibus has never been inspected by an engineer (and I'm assuming not as there was no damage to it) then the insurers aren't to know! Insurance companies have a duty to keep the costs as low as possible - inflated or fraudulent claims don't just have an impact on your premiums, they affect everyones! And, if an insurance company has enough evidence to avoid paying out unnecessarily, then they will take it! I would advise talking to them rationally - you are their customer, and they will act in your best interests (economy allowing!)