No Communication!!

The medical aid claims I have an overdue amount on my old medical aid (Classic Plan) I was never made aware of this telephonically or via email (although they claim they made contact with me which is not true) they did post a letter to me dates April 2017, and I only recieved the letter in August 2017 (the Post office is not really the best option) upon receiving the letter, I did not dispute their claims and went on to pay the amount stipulated on the letter. 2 days later I recieved a call from an external debt collection company telling me that my account was handed over. Given the fact I had paid Disovery according to my knowledge and the fact that we can't trust any call centers these days I was not willing discuss any personal details with them and instead called Discovery directly to enquire about this. During the phone call, I was advised that I had paid in the full outstanding amount, and did not need to pay any external company an amount. I even requested to be sent some documentation staying this which was then sent to my email. About 2 weeks later, I got an SMS from the same company stating I owe them and the account is accruing interest. I again called Discovey with out any help, and again lodged my query via email with no response until I sent another follow up email. Only then was I informed that my account was handed over and I needed to pay the admin fees for the external company!

Now I am very angry because despite my attempts to call and find out I was advised I don't owe any further amount! And I reckon it's misleading to me that all of a sudden I need to pay more money; and had I been told sooner about this- I was not gonna be charged any further interest on that amount! Some one needs to assist me m!!