Worst Medical Ssheme

I gave a month's calendar notice to terminate my membership as I have joined another medical aid. The message from Fedhealth reads, "Kindly settle outstanding contribution by 17 March to avoid backdating of termination and possible reversal of claims." The number provided in this message does not even work. Since when does an individual pay in arrears after joining a scheme? My monthly contribution will be deducted month end after joining the new medical aid on 1 March! I don't appreciate messages like this as I was a member of Fedhealth for many years!