Upgrade without premission

During October 2015 my son went to Kollonade with all his documents to upgrade and change contracts that was under my name to his name. He presented his ID, proof of income and bank details, Vodacom upgraded this contract *******ly under my name again and debited my account now for several months without permission. I have phoned Vodacom in Decmeber 2015 to investigate and correct it but since my discussion with them had no feedback at all.<br> <br> How can Vodacom upgrade without my consent, why did Vodacom ignore instructions from my Son to transfer the number to his name. <br> <br>