Nicole Davis & associates harassing me for payment settled

Good Day, Kindly assist me getting Nicole & Davis off my back. This people are harassing me with a claim that they represent Medi respond and that I should pay them over R4000 for an ambulance that took me and kids from an accident scene to linksfield hospital 16November2020. Medi respond send me an invoice January 2021 which I paid in full for amount of R2500. They come and disappear.