Staff using clients phones for private use

I am disappointed.I had a Samsung S5 and within 6 months the phone did not come on,I took it to Roodepoort to be repaired.There were a number of things that needed attention.After that I realized that the screen was lifting and contacted Samsung.I was then contacted Siyabonga Skhosana who collected the device.After collection he did mention given the history of the device it will be replaced and gave me a turnaround time.To my horror my device was been used by the staff over the weekend for private use.This was discovered by my boyfriend who called me via Viber,the app was active and a guy answered.I contacted Siyabonga on Monday morning,he contacted later stating the device was taken home by a technician, so the device left the premises of Samsung without my knowledge and my applications was still active violating my privacy and Samsung went against the POPI act.I asked him if the technicians repair devices at their homes, he stated NO, said that it is not Samsungs policy.Today I received a blunt email from him stating the device has no faults and will be returned.Does Samsung return phones to clients once their staff have used them for their private use. I refuse to accept.