Bad Communication - RCS

I continue to have problems with RCS, specifically the Smart Shopper Credit Card. I have complained on Hellopeter about them before. My last statement for my Smart Shopper Credit Card reflected R71.34 interest. This surprised me as I pay the balance on my statement in full on time every month. I queried this and I was informed that the interest was on an outstanding balance. I pointed out that there was no outstanding balance as I paid the full amount on the statement. Now, I am informed that when I transact a purchase at the Pick n Pay, cashier, I should put the transaction on 6 months to ensure that the purchase is interest free. I found this strange as I would not want the purchase to be over 6 months. That is why I indicate 'Straight'. Now, what is disturbing is that this was of working was never explained to me, even though I have used the Smart Shopper Credit card for about 2 years. Also disturbing is that the Pick n Pay cashiers never pointed this out to me. Why are they not trained by RCS? In any case, the other credit cards I use, work in a totally different way i.e., so long as you pay the full amount reflected on statement, there is no interest due. So this way of working with RCS, is different and customers ought to be informed of this. RCS suffers from 2 problems, communication and administration. In the Pick n Pay stores I use, the store managers have expressed their dissatisfaction with RCS. I have found the Pick n Pay store managers always helpful and the Smart Shopper card having positive benefits but RCS, undermines customer good will. I wonder whether other Smart Shopper Credit card users have experienced poor treatment from RCS. Let me end by saying that I now understand the strange workings of RCS and will in future, when making a purchase, indicate 6 months, although I will pay the full amount reflected on statement.