MEDICAL AID ACCOUNT PAID MONTHLY AND NOT UPDATED, HANDED OVER

I had medical aid with discovery and had an outstanding amount of R6000 to settle. Discovery contacted me and I agreed to a payment arrangement of R200 monthly as of October due to financial constraints, they a advised they will review the account in 3 months to make another arrangement. On the 10th of October I paid R1000 and on the 09th of November I paid R1000. To my surprise this morning I have been contacted by ITC debt collectors on behalf of discovery saying I was handed over on the 21st of November 2021 for an amount of R5000. How am I owing R5000 when I have paid R2000 already and what happened to the payment arrangement that was in place done telephonically? I was contacted by Naledi Samuel who said her supervisor was Sarah and did not know her surname nor anything prior to my account. I want all the call recordings and an explanation of this.