Promise broken

My Sister bought A Vodacom kicka 4 plus cellphone with Ok Furnitures in KWT the one next to Shoprite last Year October but a few days later the phone was faulty en took it back they did not want to refund her then they took it to repairs en promised to bring it back to her by the 15th of December but up until this day she has not received her phone back en everytime she goes to them to check what is going on they keep on teling her the phone is not back and they are not getting through to Vodacom like that is her fault.my sister has been without a phone for almost three months now and she is unemployed she cant afford to buy another phone...her Name is Ntombekhaya Waphi with ID No ***.we urgently need assistance because she is looking for employment en now we dont know if she is missing out