Disgusting harassment from RCS

I have my RCS account for a few years now and has always paid my account on time but with the Covid pandemic, things started to get tight for me. Still I paid my account every month, sometimes struggling to do so until a couple of months ago I happened to pay my account a week late, but still I paid! This is where the phone calls started, I have since paid my account on time every month, but the calls keep coming, at least twice a week and some times, like today, twice on one day! I am not behind, I paid the amount due in full on the 30th but today on the 6th I am being told to pay my full amount that is only due at the end of the month immediately. This is blatant harassment and complete disregard of my installment dates due. I do not understand why they now insist that I pay an amount only due at the end of the month, especially in these difficult times. I feel I do not need to pay them anything but still decide to pay R385 as it is all I can now, but they phone me and say that I didn't pay, I even paid and cleared the amount. I am being treated like a ******** and they talk to me as if I am a child. I am 53 years old and do not deserve the treatment I am receiving after being an excellent client for many years. Very disappointed and disgusted!