I want what I paid for back!

I purchased a Samsung phone. After 5 months the phone refused to power on. I logged a return and they picked up the phone. I requested a refund and they declined it. After several mails to have them return the R10 000 phone they refuse to reimburse I Still have not received my phone or any communication. This is unacceptable and theft as I have paid for the phone, they took it back refusing a refund BUT not returning it to me. I can have it fixed myself! I want my phone back