I need them to respond and clear that amount before the 15 of AUGUST

I'm having a huge problem with MultiChoice they have decided to double my instalment from R539.00 to R1 039 and I have been calling them 10 times to fix my account but until today its not fixed and they admitted that the problem is on their side they told me that they have charged me by mistake because of the upgrade Reward that I won from their competition so they will fix my problem withinb 24 hours but that never happened