(MONEY Magazine) – Steve Kanstoroom Oxford, Md. When Hurricane Katrina struck, many on the Gulf Coast didn't have government flood insurance--and they paid the price. But even those who did have it are getting hung out to dry.

So says Steve Kanstoroom, anyway. He's been on a crusade ever since his home was hit by Isabel in 2003. Adjusters offered only a fraction of the money needed for repairs, so the retired credit-card fraud detector read the fine print and got the software that some claims adjusters used to make estimates. His conclusion: Payouts were based on new-construction prices, which are lower than repair costs. Kanstoroom cried foul. Thanks in part to his efforts, in 2004 the National Flood Insurance Program agreed to review any of the 24,000 Isabel claims, and $8.2 million has since been doled out. But Kanstoroom contends that FEMA, which administers the insurance, has repeated its mistakes since Isabel. (The agency would not comment.) So he's helping other victims get their due via his site, Femainfo.us. His advice could apply to any insurance customer: "The best defense is knowing what you're entitled to."