Visitor insurance – is it a scam?

Hi everyone,

Need some guidance on visitor's health insurance.

My parents are visiting me in the US and I took visitors medical insurance for them. I took the insurance the day after they landed. I used the insurance when I took my parents to the doctors at the hospital. I paid the deductible. Now I see the bill on the father's hospital account for a huge amount. Insurance didn't pay their part of the bill.

I called the insurance people and they sent a "Notice of claim processing" saying that the bills aren't claimable with the remarks "Policy purchased after the trip start date. Required health attestation form not completed".

I didn't see any message when I bought the insurance that it MUST start from the trip start date. It started 2 days after they landed in the US. I didn't receive any health attestation form to complete.

Anyone experienced such issue before? How to deal with this? Any suggestions are welcome. Thanks in advance!