Incorrect amounts given. No membership card received. No feedback

We have an email from discovery stating our arrears amount. We have made the exact payment of R2786. 00 for us to be reinstated on the medical aid. Then another consultant from discovery send us an email that they have received the amount but we have to pay another ''R5936''. Not stipulating for what or why and why didn't the first consultant give us this amount, and even how did they come to the bigger amount when our montly amount is not even R1500???

We have asked the consultants to call us back but no reply on emails and the contact number just rings with out answer.

We have been on this plan for 6 months and after many times asked for our membership card we have not received it.