Incorrect billing but I must just pay

I upgraded my contract and added a 2Gig data bundle that they said equals 4Gig (2 + 2 free).<br> When I got my bill, I was charged R 5000 + for packet switch data.<br> The bundle was loaded on my other number that I own with MTN and not the number I just upgraded.<br> They then fixed it to be on the right number but still expect me to pay out of bundle rates for a mistake they made.<br> Not to mention that my credit limit is set to R 1 700.<br> I tried to phone, email, facebook and the run-around is so ridiculous.<br> I know you dont care about me as a client, whether I leave or stay, it wont matter, you will just continue to ***** from others. It seems the only way to get your attention it to purchase a billboard in Sandton. Maybe I will use all the effort I have already wasted on you to rally people who all complain about the same thing, your pathetic service, and organize a nice billboard for you. I know I would at least feel better and my money would be put to good use and not just handed over to you. You definitely do not care about your clients.