6 month Interest free doesn't exist

I recently made a purchase at the centurion edgars, instructed the (***********) cashier to place my purchase on a 6 months interest payment. Received my statement, notice my purchase was placed on interest baring plan. Contacted Rcs/edgars customer services, afters many emails I was told I have an 6 month interest free account which has interest charges. It takes days up to a week for a reply. Clearly if RCS is inundated when email queries they are definitely doing something wrong. There is a additional monthly FEE charge. What BULL**** , can't wait to pay off and close this **** account. Had my account since 2001. Everything was excellent till RCS took over.