Unauthorized Amount Debited

I RENEWED MY CONTRACT A FEW MONTHS AGO AND WAS INCONVENIENCE TERRIBLY BECAUSE I WAS PROMISED A CERTAIN COLOUR OF A SPECIFIC PHONE AND AFTER SOME TIME OF SPENDING ALLOT OF MY OWN MONIES I OT MY PHONE. NO REFUND OR CREDITS WERE GIVEN . I SPENT OVER 1000'S OF RANDS .THAT IS NOT WHY I AM EMAILING. .I AM EMAILING BECAUSE I'M BEING DEBITED FOR LARGE AMOUNT AND NOT WHAT WAS AGREED UPON. I SIGNED UP FOR A CONTRACT AT - 769.00. . I ALSO ASKED THAT A LIMIT BE PUT ON WHEN I ACCEPTED THE PHONE. I WENT OVERSEAS AND REQUESTED ROAMING AND THIS WAS ACTIVATED. I HAVE DONE THIS IN THE PAST AND NEVER HAD ISSUES WITH BEING OVERCHARGED. I DON'T SEE WHY I SHOULD BE DEBITED SUCH RIDICULOUS AMOUNTS WHEN I STATED I WANTED A LIMIT PUT IN PLACE . MTN HAVE INCONVENIENCED ME SINCE THE TIME I UPGRADED TILL NOW. I TRY CALLING THE CALL CENTRE NUMEROUS TIMES AND HOLD TILL WHENEVER .MTN'S REPUTATION HAS NOT BEEN GOOD AND ALLOT OF PEOPLE LIKE MYSELF HAVE SUFFERED IN THE PROCESS. I NEED SOMEONE TO CALL ME URGENTLY.. I GOT AN SMS SAYING I SHOULD PAY TO AVOID LEGAL ACTION BUT IM NOT AT FAULT. I WILL GET LEGAL ADVICE. THE BIGGEST MISTAKE I MADE WAS TO RENEW MY CONTRACT.