Claiming amount that has been paid 17 months ago

Good day, on the 25th of June 2018 I was rushed to the hospital for labour pains & when I got there I was given a form to complete in order for the doctor to attend to me, I was then given a drip to reduce the pains then the doctor said he will call an ambulance to take me to public hospital which he did & the ambulance demanded R500 cash before transporting me which we paid same day. I gave birth on the 30th, during the month of July 2018 we received an invoice from Bougainville hospital with an amount of R980.00 which we paid on the 06/08/2018. A year later (September 2019)I receive a call from Anna at vericred claiming the very same amount that we have paid including their accrued interests and I emailed her the proof of payment along with the invoice I received from the hospital and she called back confirming that there has been a misallocation of payment. A month passed then November 2019 I received another call from some lady at vericred and I referred her to Anna she called back and said she confirmed with Anna all is sorted I even drove to Bougainville hospital accounts department for more info and they couldn't give me a clear answer regarding the handover. Today on the 9th January 2020 I receive a call from Nicole from vericred claiming amount that has been paid 17 months back and when I told her to ask Anna for proof of payment she said Anna was not around then hanged up. Bougainville hospital has not made any effort to contact me regarding any debt until I received a call from Vericred. Vericred stop harassing me to pay an account that has been settled in full, get this sorted as my account is settled in full. Please contact your client which is Bougainville hospital in this regard to confirm that my account has been settled and next time when you call me you should call to thank me for payment and close the acc cause clearly it was wrongly handed over.