Deduct money without permision

Telkom upgraded us and deducted the amount (which is double our installment). Which we did not agree to at all. They have phone call recordings of it. I have been complaining since beginning of January, and no moneys have been repaid and no one wants to help. They refuse to correct it! When you phone at mobile rates they keep you on hold and have no clue how to correct the problem. I have emailed and phoned and gone according to protocols. Nothing at all has been done.