Terrible treatment by AMPATH LABORATORIES

I made a payment arrangement to pay for blood tests over 4 months. I missed one payment - the smallest payment - of the 4 - the last one - as I thought I was done. I received one sms - then in a week was handed over to debt collectors! I tried to speak to the accounts department - only to be met by the rudest of rudest woman who is in charge of the whole accounts department in the Pretoria Branch. She insisted that I cannot juts pay the amount outstanding, but now I have to pay debt collectors nearly double of what the last payment would have been! When I said I will pay tomorrow once my salary came in - she refused and said I must deal only with the debt collectors! I WILL NEVER USE THEM AGAIN AND I HOPE EVERYBODY READING THIS WILL NOT EVER USE THEM!!!