DOT won't help because it has absolutely no authority over insurance or financial products. Whether this is a UA or an Allianz error will determine which type of product. But, you can save yourself a lot of time by just doing the following.

I would wait until the routing on the ticket has been completely flown. If this is a OW ticket, that will occur tonight. Reason is that systems do cause cancellations, so leave it alone if it is RT, until the return is flown (but note that there is no legal requirement for a chargeback to be honored after 60 days, so calendar the date.

Simply send a note to UA and to Allianz noting the error and requesting a refund.

If the refund is not issued in some reasonable time period, give it a week, file a chargeback dispute with your CC issuer for the amount of the insurance. Be clear that it is the insurance.

You will then have a temporary credit which will become permanent when neither UA nor Allianz bother to respond to their merchant vendor processor.