Closing my account after 40 years due to new terms and poor service

I called Edgars customer care to query why on my purchase of R255 in September, I have to pay R100 minimum payment? The consultant was so rude and impatient and kept saying because its a revolving account. I still don't understand what that means and why I have to pay it off in 2,5 months, if I have an account. I used to have 6 months interest free to pay the account. I could just as well pay cash or use a credit card now. And the interest is 20,25%! No point in me having an account as there is no benefit, so closing it after 40 years. I told her how long I'd been with Edgars but she didn't show any concern with losing such a long term customer. They really need to train their call-centre agents better.