Wrong Debit Order Date

In 2019 I got a call from on OnAir they said they are calling on behalf of Multichoice and they explained that my decoder has expired so I need to upgrade to explora and I had no problem with that our agreement was that I will start paying in November the last day of each and Month. In November they honored our agreement, the problem started in December they debited on the 29th lucky I had cash in my account and now in January they did the same and I had nothing in my account as I wasn't expecting any debit order because I'm not paid yet. What makes me angry is that who will pay the money of the debit order that bounced? :-) I tried calling them but no answer