unable to fix a handset under warranty

I bought a handset for R2799.00 at hi fi corporation festival mall last year december and I was told that should I encounter any problem with it, I should bring it back to the shop as long as it still under 1 year warranty.I started experiencing problems during calls where I can hear the caller but they cant hear me on the other side.so I took it back to the shop and they send it to their technician who took morethan 21 days to repair it. It came back with the problem unfixed and I went back to the shop to lay a complain with the manager who told me that In order for the problem to be fixed quicker I have to take it to their technician by myself.what a bad service... its a waste of money,energy and time.im not impressed and I will never ever buy from that shop again...