Health insurance claim checks question.

Hi insurance!

I have a question that all my searching comes up with nothing.

Here's the situation. Me and my wife paid a midwife for a home birth a flat fee of $5500 for her services. Everything went perfect!

After the birth the midwife recommended a third party billing to see what we could get insurance to cover. So far so good.

Claims are submitted and approved/denied. My question is just on refunds we are receiving from insurance.

Third party billing charges 10% that is okay with us.

Final EOB is the following:

Insurance allowed for service: $6476.48

Co-insurance: $1706.25

Deductible: $776.81

Insurance Paid: $3993.42

Client eligible: $3016.58(flat fee – (co-insurance + deductible))

Billing fee: $399.34

Remaining amount to send midwife: $577.50

My question is why does the midwife get any of it? She had a flat fee and agreed that it was paid in full.

Just trying to understand before I send out $577.50.

Thanks!