Terrible service

Two months back in January, I took my Grand Cherokee to Jeep Grand Central Motors in Midrand for a car service. Upon collecting my car, suddenly the car couldn't pick speed, that is, loosing acceleration power and I was told stories of how some rims have run out and needed to be replaced. Something which I didn't have when I took my car there. Then I was told of how they were going to order those parts and that it was going to take a week for them to be delivered. I then took my car back to have those parts fitted in. Upon collecting my car, suddenly the GPS wasn't working and I was told of how it might be new to the new software. I was asked to bring my car for them to check if the problem with GPS wasn't because of the software. I brought the car the next day and some white guy, can't remember his name, took it to the back to have it checked and I was told the problem wasn't the software and that they needed to replace the whole radio system. I was told that radio system had to be ordered overseas and it was going to take almost 4-6 weeks to arrive in S.A. On the 20th of this month, I then called Grand Central Motors to check if that radio system hasn't arrived as I'm battling to travel without the GPS. I spoke to the lady by the name of Bontle who has been assisting me from the time I brought the car for service. Bontle told me of how she was going to check with so and so from the back and will come back to me within a hour or so(I was just irritated by whatever she was saying and couldn't even get to hear exactly what she was saying). By the way, I spoke to hear early in the morning and by 3 I still haven't received her call back. I then called her back and she told of how she has been told that I must bring in my car to have the software checked, mind you, it has been checked and confirmed that the fault is not related to the software. I mean how many times must it be confirmed that the fault is not related to the software? And every time I take my car to them, I loose income because where I work, it's no work no pay and the worst part, you don't even get a courtesy car from them let alone they are not even prepared to collect you if you are based in Joburg. You know, I'm starting to hate this car because for the amount it is worth, one doesn't deserve all these problems. I wish I had bought my car from somewhere and not them maybe those people would've treated me otherwise. Now what am I supposed to do with such a big car that doesn't have GPS? With this kind of service, I doubt that I will refer anyone to buy or let alone take their car for a service there. I'm just ****ed that I'm even contemplating taking this matter further to the newspaper!