MTN taking what doesn't belong to them!

Hi I am really very upset with MTN a service. I spend more than an hour on the phone trying to get MTN to answer my call. My contract number is ***. My debit order is supposed to be 579 and did go through. YESTERDAY DOUBLE OR More went through my bank. I WANT NY MONEY BACK AND A PROPPER EXPLANATION AS TO WHY THEY *****ING.!!!