*********** service and not acting in interest of Discovery client

I have an invoice to submit every month with rule exception letter and stamped paid invoice. This is the 3rd time I am questioned if I paid the supplier and after their rule and instruction that I must send the PAID invoice with their letter they pay the supplier! I asked many times does Discovery know of a pharmacy that dispenses medication WITHOUT PAYMENT. I am now asked to provide my proof of payment despite a stamped invoice PAID being provided together with Discovery letter. I requested the consultant to call the pharmacy and get the proof of payments. Also provided her the letter from Discovery with their particular instruction to send the Rule Exception letter with PAID invoice to claim