Billed for a Remedial - who do I contact?

My son was directed to undergo a remedial for asthma. He went to the provider Concorde directed him to visit and had it done. Yesterday, in the mail, we received a bill from that provider noting what Concorde had paid and telling us that "our portion" of the bill of $69.00 dollars and requesting immediate payment. Do I need to call the Office that did the remedial or call Concorde on Monday about this?

This was a DoDMERB ordered remedial done at the facility Concorde directed us to, so...

Billed for a Remedial - who do I contact?