A medical aid or money making scheme for the practitioner?

When a claim (already paid by patient) is submitted, showing no balance due and with the instruction that the member is to be reimbursed is submitted, Discovery is quite willing to incorrectly pay the practitioner.

When the same claim, now signed and stamped by the practitioner, stating that it has been paid is submitted - Discovery refuses to reimburse the member as there is insufficient proof that it has been paid.

At the same time another claim, from a different practitioner, stating that the amount is due, without any proof of payment.... that can be paid out!

Where is Dicovery's ethics and loyalty?