Vodacom '*****' from customers!!

I am on Red Premium, therefore paying over R2000 per month. I get 10 G data a month incl in my package, and because I had a problem with Vodacom before, I always check my data usage. On the 3rd of May, I watched movies on Netflicks – I monitored my databundles and when I saw it is running low, I bought 3 Gig data. I again watched movies on Saturday and again bought 3 Gig. It did not show immediately but I received an email that I bought it, and I continued watching. When I check my balance on the 12th of May, it showed that the 6 Gig I bought was still in my account but my bill is standing at R8000!!! Vodacom has probably charged me out-of-data-bundle rates for the movies I watched.! It seems that they did not use the data bundles I bought but instead charged my out-of-data bundle rates?? As a red premium client, we are suppose to receive 'very special treatment'. I have emailed Vodacom 3 times already and has had no response! Vodacom is a ******* and their customer service is non-existent!