Insurance Not covering accident. Options?

My mother was in an accident while working (contract delivery driver). A few days after the accident her insurance company emailed her and said she has no coverage because she was working in her personal vehicle and didn’t have commercial insurance.

She had this same job for 30 years. Shes used the same in-person insurance agent then entire time. The agent knows she was working with her personal vehicle because she delivered to his business. They have covered prior accidents including a total loss just over a year ago. Now obviously from everything I’ve seen in the communication she’s received she did have the wrong insurance I’m not arguing that (and yea she should have known what she needed).

Has anybody ever dealt with a situation like this? Does she have anything to go on? Maybe negligence by the agent?

Thanks