Bad Service

Hi, on the 1st of Sept 15 I upgraded my Vodacom contract to a Sony Experia M4 Aqua. We had it for 2 weeks then the bottom speaker became faulty (we assume) since he can us but we cannot here him. We took it in for repairs at Vodacom in Southern Centre Bfn who then sent it to their branch at Waterfront. Saturday it will be 3 weeks since we took the phone for repairs, i spoke to them to today and they advised me that the phone has been sent for 3 party repairs i.e Sony Repairs. I spoke to someone who said that it might take anything from 10 to 21 days. This I think is totaly unacceptable as the phone is practically brand new. I am therefore requesting that a new phone be sent to us a.s.a.p cause I really think it is poor for a phone to break only after 2 weeks and it is also not the first time this happens to us with a sony phone.