Unfair Practice - Discovery Medical Aid

I joined Discovery Medical Aid in February this year and was asked to pay a cash sum of R3000, following some blood tests for my chronic meds. We inquired if this amount could be deducted from our savings and were told that this was not be possible and we would have to pay from our pockets or we would loose our cover. As we have always had medical cover and were afraid of something happening while not covered, we did an EFT the same day (end of Feb 2018). We soon then discovered that Discovery also deducted this amount from our savings (even though we were initially told that this was not possible). We have sent numerous e-mails asking that the cash amount be re-funded but have not even received a response in over a month. I think it would be fair that Discovery now pay this refund, as well as any interest that would be due if this money was invested in my bank. Why is it that payment is always urgent when it is owed to Discovery and various conditions are placed, yet refunds take ages and no conditions are expected?