Dysfunctional Samsung6 repaired for third time

I upgraded to a Samsung6 on 2 June after having had a contract since 1999 with same no. From the start nobody could hear me properly: severe distortion or echoes heard. After a failed attempt at 'repair' I booked it a second time, job no. ***8. After being informed 8 times that it is in the 'quality assessment process', I was instructed to collect it at Menlyn on 13 October with the report that even for the second time no fault could be found. The problem persisted - both Vodacom Customer Care and the branch could not even hear my surname. I booked it for a third 'repair' on 22 October with job no ***7, but now a 'Portia' responded kindly, but having emphatically refused that device ' Divan' under EC-OXNM-3CFVZQ6 liberally promised a CPA REFUND: I would be credited to buy an alternative of my choice provided that they find it faulty. I am a professor at the Shool of Medicine, UP, and cannot do my work effectively either with students nor with patiens. They have good intentions, but now get no response from my e-mails, despite the fact that the device clearly is dysfunctional. As said my work is under severe strain: working with defective phone, can at least be heard.