Poor service

I took my blackberry 9720 in for repairs on the 17 January 2014 as it is still under warranty. They let me know that they are going to exchange the unit and I was happy. But once the exchanged unit started giving problems, I noticed that it was a refurbished unit and not even the one I gave in. I bought a brand new unit and if its faulty, I'd expect to get a new one back, but I got a refurbished one back. I sent Vodacom an email on there website, but haven't got a answer as yet. I just feel that I could have bout a good 2nd hand phone for the same price as buying a new one. <br> On top of all this, I loaded 5GB of data on Tuesday 25/3/2015 at 12:39. On Wednesday 25/3/2015, 15:32 I noticed I had 3.97GB left. I have a blackberry, so there's no apps running in the background. I went onto mobile hotspot to check for pictures of work related things as samples and ideas for a client. But soon logged off and watched dvd's all night. I bought the blackberry phone to save on data and in a matter of a short period, over 1GB was used. This is totally ridiculous. I called 155 on the 25/2/2015 at 16:02 to complain and they said they would follow up and get to me within 24 hours, which was not done