Nonsense service from Imperial Select Fountains

I bought a vehicle in 2015 from Imperial Select in Schubart Street, Pretoria. I found out this year that the tracking device was not activated, but paid for. After further investigation the bank sent me the invoice and I found that Imperial Select invoiced the tracking device for more than R4000 (excluding VAT), however, according to the tracking company, Imperial Select only paid them +- R3000. I have been trying to get an explanation from the branch in Fountains for a very long time now. The stock controller (Jeana) was very helpful in the beginning but since that first call when she 'mistakenly' took my call, it seems like either she is avoiding me and my numerous emails or I don't know what else could be the reasons. On one of my emails I even asked that if she is unable to assist she must just give me the details of the person who could assist. I even spoke to Nicolette also on one of the occasions and the call was cut, but no call back. I call almost every week but the receptionist just takes a message and promise that Jeana will call back. So since she cannot answer my calls or call me back, I would like to hear from Imperial Select, do you normally charge more and then you refuse to explain?????