Unauthorised payment from my med savings account

My optometrist submitted a claim to Bestmed for R3010 in 2015. Bestmed paid the optometrist R760 and R876, leaving a balance of R1374 not paid by Bestmed. I paid the optometrist R1374 from my pocket and then submitted a claim to Bestmed for R1374 in 2015. Three months later, numerous e-mails with supporting documents, calls not answered by the call centre, and I am still waiting for Bestmed to refund my R1374. After another e-mail requesting my long overdue refund, lo and behold, Bestmed proceeds to pay the optometrist an additional R3010 from my medical savings account when no money is due to the optometrist at all! The optometrist was paid, in full, in 2015: R760(Bestmed)+R876(Bestmed)+R1374(by me)=R3010. So, the optometrist was paid twice, and I am still left out of pocket to the tune of R1374. At no stage did I authorise Bestmed to make a duplicate payment to the optometrist. Bestmed please resolve the spectacular mess you created. 1) Credit my savings account with the unauthorised duplicate payment of R3010 and 2) refund my R1374.