Bonitas accounts department. Incompetence at the highest level

I resigned from Bonitas Medical Aid several months ago. At the time Bonitas owed me an amount of R 12 237.60. When I requested the refund they categorically sent me an email stating that I had overspent on my day to day medical and they will deduct the said amount of R 5004.00. I agreed to this and was paid out the balance of R 7233.60. However during the week I received an email stating that the amount of R 5004.00 is still outstanding. If I don't settle they will hand me over to a collections agency. This is absurd since they already deducted the amount from the credit owed. " DOES THEIR ACCOUNTS DEPARTMENT REALLY KNOW WHAT THERY ARE DOING" I sent them an email and have still not had a response. Fellow South Africans please be aware of the incompetence from Bonitas medical Aid. Membership No : ***