Discovery doesn't pay

Earlier this year, I submitted a claim to Discovery for reimbur*****t of a medical bill settled late last year. It itemised all the amounts that I had paid and the service provider had confirmed that I had paid all of it.

When I checked the payment, they had only reimbursed for the last visit.

Does Discovery now expect me to produce each individual invoice instead of showing them the statement of all that was paid for the course of the treatment over several months?