Bad service from Er Dr Holtz and Partnets

I took my son in to Mediclinic Trichard Mpumanga the 21 October 2020 as he was injured and he was attended by Dr Holtz and Partners doctor the same night, everything was sent threw to the medical insurance which was oneplan, and payments were finalized then on the 29 January 2021 I received a call from a rude admin clerk working for Dr Holts and Partners fighting with me for a doctor's account of 876.00 I asked her did you contact the medical insurance she said she never had the details but all the details was captured at mediclinic Trichard, she was atually fighting with me on the phone, bad bad service I must say you don't treat people like how that lady spoke to me over the phone, I called my insurance they said they never received any invoice or account for doctors costs I called back and asked for a supervisor or manager to call me back because I do need a appolgy but nothing until now, will never use them again terrible service very dissatisfied.