forcing my sister to pay what she did not buy

Khunjulwa took a contract phone with Cell-C network providers using my sister 's details yet Cell-C were able to give him/her the phone now they want my sister to pay. Please stop making people 's lives difficult. I believe if one is buying a contract phone they bring ID book and the salesperson must ensure that the person buying is the correct person. Unless salespersons are the once doing *******ion. Please find out who sold contract to Khunjulwa Nika using my sister 's details