Paying 4 months for a tablet i don't have

Good day people. I am having problems with Dot FNB in Cradlestone mall. I took out a tablet from them in January 2015 but returned it\ still sealed in the box"the same month for a bigger one and sins then i have been having problems with them taking money from my account for over 4 months now!!! I went to them + -6 times and the lady there is still telling me that she will sort it out for me and will \""call me back\""..I sent a complaint to the head office and with no response! Every time i call them it costs me a lot of airtime and when i go to them it costs me petrol that is not cheap these days! I called them yesterday and they say to me that the manager is out and will call me back..i called them today again and still nothing!! If they don't sort it out this week then i will take further!"""