It is not unusual for an insurance company to depreciate the value of
the item being repaired or replaced. You would need to review your
policy to determine if that is allowed in your case.

The first action you can take is to question the valuation with your
agent. They may pass you on to a claims adjustor. An explanation of
the repair might get you a better assessment.

If you intend to challange the payout do NOT cash or deposit the check.
It may be taken as accepting the offer.

How far you go with the matter depends on the cost of the repair, what
your deductable is, wether you can find another insurance company if
they drop your coverage.