No update, very delayed turnaround time

At the end of April I walked into Cellucity & bought a Sony Xperia Z3 compact in cash. After only having the phone for 2 weeks I had to hand the phone in as it wouldnt charge. The phone was repaired & I received it back 2 weeks later. A few weeks later I had the same problem. Handed it in at the store I bought it, explained the situation & requested that I either get a new phone or get my money back. This happened on the 16th of June & was told it would take 7/8 days for a response but was given the contact details of the assistant dealing with the matter. After a few days I contacted her as nobody had kept in touch, she said she would email me that day. She didnt so 4 days later I phoned her again. She then emailed me to tell me nothing could be done except wait. She told me it would take up to 2 weeks for them to assess the situation & then take a further day or 2 to receive a replacement or refund It is now 3 weeks since I handed in my phone with not once receiving a courtesy sms, phone call or email from neither the store I purchased the device nor Vodacom themselves. I dont know who has my phone, what is the hold up, how long it will take, why its taken so long to resolve