Unable to close my paid off account

I've been tormented by these attorneys since 2016 for a collections on behalf of Dr Kumin, a Paediatrician in Sunny side. My daughter was born in 2015 and the medical aid failed to pay due to my child not being registered on the medical aid, the matter was settled and the amount fully paid, a year later, same attorneys contacted me and I send them the proof of payment and the case was closed. Now ,2 years down the line you're still claiming from me even after I've contacted you telephonically, via email, no one is reverting back to me. I'm getting fed up and will now resort to reporting you people with the relevant body's/authority.