Online order cancelled by Makro and they won't refund me

I bought some bottled water from Makro online on 20th June. Total amount of basket was R530. On the same day 20th June R50 was refunded to my credit card. Don't know why. On 2nd July Makro cancelled my order giving reasons that they are having problems with their supplier. They told me my credit card would be refunded with R480 (less the R50). The only form of communication with the company is their 0860 number or an email which goes to the same call centre. 8 emails later and 4 promises that authorisation has been given for the refund, and to date, no refund. I will NEVER buy @makro online ever again. How do I get my money back. The worst ever service I've received in my life. I can't even phone their head office to follow up for me. I've given 3 people my phone number and order # to call me back. Nothing!