TERRIBLE SERVICES!!!

We bought a brand new phone from Cash Crusaders Randburg branch and within the first 6 days the phone stopped working we took it back on the 8th day and was told it has to go for repairs and cannot be exchanged or refunded.......cool they send it in for repairs we told come back after 2 weeks if we not happy we get a refund or switch the phone for another mind you they then take the receipt away from us now and dont give us a copy of the receipt......we come back after 2 weeks still not fixed....they tell us come back the following week which is this week.....the phone has been used to hack into our social media accounts and bank accounts... when tracking the activity log its traced back to that same phone....we go In today to get the receipt and see the status of the phone repair and they are STILLLLLL not done and now are charging us a fee ontop of all the run around and inconvenience.....how can we resolve this issue ASAP please as this is incompetence and unprofessional on the highest level!!!