RCS interest rate shock

As a loyal customer of RCS, a subsidiary of Foschini with whom I have an account dating back to 1975, I was a satisfied user of the RCS Credit Account. This was until the 12th of June this year, when I was informed that RCS is able to take any interest value determined on the amount of credit a person uses up until the 12th of each month without notice or agreement. This then means that accompanying the interest already paid on the account on the 7th of each month (financial end of month), RCS decided to take a staggering R700 interest. <br> <br> Upon query the consultant informed me that this was due process but this is the first time in the nearly 10 years that I have used the Credit card that such a thing has happened. Clearly the CPA of RCS is being used against me and this is unacceptable. This remains unsolved.