Worse Service ever on a Isuzu with only 40 000km on the Clock

We have only driven Isuzu bakkies (on count now more or less 9). We purchased our current 4x4 for the business as we started a 4x4 Fitment Centre. We take very good care of our Bakkies en uses this bakkie vir shows and exhibitions most of the time. The only gravel road we travelled was during our holiday in Botswana in August. In November our Bakkie suddenly just lost power on our way to work we barely managed to get to work. The branch where we bought our Isuzu in Ferndale had been closed down and we the bakkie was picked up by Isuzu Stellenbosch. The Sales manager of Ferndale move to Stellenbosch and therefor the choice of Dealership. The Management team of Ferndale was aware that we had put a Chip in our Bakkie. When this problem occurred we immediately asked if the Chip could be the problem and we receive a VERY DEFINITE NO from the dealership. After 2 weeks they mentioned that it was the Injectors and maybe filthy diesel, but they were not sure. Then after another 2 still no reply or fixed vehicle. We had to cancel holiday plans as we needed a 4x4. In the new year we had to follow up with still no clear answer from them. At this stage our vehicle were with them for almost 2 months. Now suddenly they claimed that the Chip was a problem and that they will carry NO Costs neither honor the warranty. How is this possible. Today is the 31 of January. We have visited the dealer. None of the managers of workshop team were there. There was bolts that were broken when they opened the engin and NOTHING had been done till today. We wrote them a mail and various phone calls with NO response from them. In the 30 years that we have dealt with Isuzu did we never receive such poor treatment and service. We feel that the faults identified in the Engin by them was Initially not that big and then after the vehicle had been with them for six weeks suddenly there is huge problems on the engin. We are very unhappy, frustrated and desperate. The quote moved from R12000 to more than R50 000. We really need some help and I hope that No other clients will take their vehicles there to be repaired or serviced.