PATHCARE DRS DIETRICH, VOIGHT, MIA & PARTNERS - A bill after 9 months!!

My mother, aged 87, had blood tests done on 20/12/2019. A shortfall of R90.02 were not covered by her medical aid. No invoice was send and we did not know about this. On 16/09/2020 out of the blue, I received a phone call from Pathcare. My (I am the daughter) phone number is on their system for several years already, which they use for sms results. But this was first contact after 9 months!! I gave them my email address. They send the bill the same day. I rep**** with info that my mother passed away on 27/04/2020 already. She had a pension of less than R1000 per month of which I can provide proof, and asked them to write the amount off. Reveiced answer that amount should be paid. I forgot about it a bit. On 16/10/2020 received an SMS that case has been handed over to MTB Attorneys, and amount of R148.67 should be paid. I am utterly disappointed in this company. To go this far for a mere R90.02, after a patient died in the meantime. And add another R58.65 to the original bill. This is the second time they did this. In 2018, after 6 months they all of a sudden came up with an invoice. Poor billing system. Took 9 months to call?SMS give other account details as invoice, for Attorneys. How do I now they are even ligit??