DISAPPOINTED WITH MTN SERVICE

I took out a Xperia Z1 at the MTN Pinelands store. Because this phone was said to be \waterproof"I tested it and to my disappointment after a few pictures and videos the phone just went dead. I took it into the Pinelands store the very next day and they booked the phone in for repairs. I called/went to the store on several occasions and every time I am promised I will get a phone call back. A month later I still have not received one phone call and am still without a phone. I understand it cannot be fixed in a day but as any person can understand"