Unfair credit listing

After I terminated my medical aid cover on 31 March 2018, I got a letter from Discovery saying I owed R2787.77 due to the fact that I overspent on my MSA before termination. The letter was written on 21 May 2018. I then made arrangements to pay this back over 10 months since I was on another medical aid and had a premium to pay. Discovery agreed to this. On 01 June I paid R350 as part of the agreement. On 02 July I accidentally paid R5000 while trying to pay R500 in an attempt to accelerate the payment period. However, in August I received a letter informing me that I have been listed with a credit bureau for R2437.77 even though Discovery had earlier acknowledged and even refunded the overpayment. I’m totally aggrieved because clearly proper procedures were not followed and someone just skipped all the necessary steps and unfairly had me listed on the credit bureau. I cannot qualify the damage this has possibly caused me unknowingly, both as an individual and a startup business who depends on a clean credit rating. Discovery Health had me listed when they were the ones owing me.