Cannot get refund

I purchased a cordless telephone from Telkom direct Rosebank on 20/06/2015. I was not happy with the phone and wanted a refund. I went to the Telkom direct at Greenstone mall where I returned the item within the 7 day period on 26/06/2915. The cashier printed out a refund slip and proceeded to refund the money on my credit card. Erroneously instead of pressing a refund he pressed a purchase and I was charged again for the phone. I went back to the store on 29/06/2015 and was told the manager is not in to authorize and I must come back the next day. I went in again on 30/06/2015 and was told the manager is still not in and will call me. I have not heard any response and nobody answers the office phone.