Lancet Refuses to Let My Medical Aid Pay for Test

On 14 July 2020 I went to Lancet branch for sampling as per Dr's referral. They took one sample. The next day, 15 July 2020, they called me to say they made a mistake in that they were supposed to take two samples and not one. So they requested me to return for the 2nd sample, which I obliged. My medical aid queried claim for the 2nd sample as there was no matching pathology report (date wise). After explaining to my medical aid about the error above, then a request was made to Lancet (by my medical aid) to correct the error so they could pay. However, Lancet arrogantly refused to correct their own error and decided they would rather make me pay. To make things worse, now they decided to have my name black listed.

Why is Lancet punishing me for their own error?