Second hand device given to me

I went into your walk-in centre in Midrand on 1/04/2015. Amanda assisted me. I explained that the speaker on the device I was given (NeoSmart) is not very clear when calls are made. I told Amanda that my parents live on the same property and use a different Neotel line and device and their line is clear, so I assume that it's a problem with my device. I asked for a replacement device to use and see if the fuzzy speaker problem is solved. After I got home, I realised that I was given a 2nd-hand device. This is not what I asked for or expected as a loyal customer. I phoned in on Thursday morning and left a message for Amanda to call me back, and I still have not yet received a call back. I am highly disappointed and shocked by the unprofessional manner in which my query was handled...and as far as I'm concerned this query has still not been resolved. I need answers and a response from Neotel asap.