Dysfunctional electronic payment system & Unhelpful Call Centre Agent

I tried to pay a bill online using my credit card this afternoon (something that I did last month) but when I tried twice I was informed on the site that: the card payment was declined and that I needed to contact the card issuer for more information." I called Capitec and spoke to a person called Nicollene who told me that they were not seeing an error message on the system. I asked them to advise what would be done to resolve the issue because Capitec needed to fix the problem, at this point Nicollene suddenly became inaudible and I was unable - after a minute - to resume a proper audible conversation with them and had to end call.