Medical aid not being reconciled

Im so dissapointed on how discovery hadle their accounts. My medical aid was terminated and they refund me R7k instead of R12k that was supposed to be refunded to me. i was told i owe them claims of R4k, thus it will be deducted on the R12k due to me, before refunding me. A month after the refund of R7k, the told me i owe them R4k of which it was never refunded to me. ive sent them emails to resolve my query, but they did not bother to resolve it nor respond to my emails. and they know saying they will take me to credit beareu. Please help me out