paying for no service

i currently have a contract with cell c. account number ***. this contract includes a cell phone and data no talk time.

on the 1st of may i moved to a place and struggled with reception. I contacted cell c and they sent out a consultant to check my connectivity [Incident: ***]. the lady checked and confirmed i dont have any reception at home. when i reported this issue i also informed the consultant that the same applies at my work place, auto and general office park. so with this information in mind, i wanted to cancel my contract because i dont have reception at the two most important places and i end wasting money and buying data. i requested to cancel my contract and i was told to return the device. i asked why should i return the device and up to today i have not received a response. i'm paying almost 500 for this contract and i struggle to get the service i'm paying for. imagine not receiving calls at home and at work. what if my child has an emergency ? what happens then ?