Complain for M***2

I went to Lancet Laborories in 2021 to do some blood test. From the form given I could not find the bloot test I needed to taken and approached the person at the desk to assist ( Lancet official) in choose the blood test sample I needed to take, the official filled out the form for me and choose the sample and the blood sample was taken and I paid for the test ,only to find after the results came in that the Lancet official chose the wrong blood test. I reported the incident to the lab and I was told to come and do the correct blood test and because it was their fault I was told the payment will be taken care of as long as I can pay the balance as there was a difference in the blood test I was supposed to be taken for the second time( the correct blood test. However payment issue was never resolved and from 2021 I have been getting the sms and email of the over due outstanding amount. I have made several call to Lancet explaining my situation and I have been told the matter will be resolved , to this day the matter is not resolved and regardless of my emails and calls I have been making to ask them to resolve the issue. Nothing has been done and I am still getting the emails and sms each month for the overdue amount.This is frustrating as my calls and emails falls in to the deaf ear and nothing has been done about my issue. The mistake was done by their office as I asked for assistance since I could not find the blood test in their form hence I approach their official who filled the form on my behalf and now I am treated as if it was my fault. The overdue amount is not much ( R138) however I am treated unfairly and this need to be corrected. I need to escalate the matter to the higher body however I don't know whom to complain to.I am disappointed by the treatment, harassed by their monthly reminders, bul**** and been treated unfairly. Especially after so many calls I have been making since 2021 and emailed to explain the matter. ***