Over charged by Woolworths

Woolworths has charged me R560.83 on a Comprehensive Balance Protection Plan for September. When I inquired, consultant Jacky Daniels send me a response saying they charge R5.00 on every thousand rand spent. My balance is R22,970.53. No apology for the incorrect charge, no explanation of how they're going to rectify the error. I am to accept the incorrect charge and pay. How ridiculous. The staff are either poorly trained and don't seem to fully understand the inquiries raised or they just don't care to do the needful.