Can't/won't fix C5

I have Citroen c5, bought in South Africa, which now seems impossible to fix. Why do companies sell you a car when they can't fix the problems that arise. The branch doing the diagnostics has had the car for 6 weeks already and they are still checking the wiring! And then the wiring must be replaced at a cost of R30000 to R40000 before they can check if anything else is wrong. The car has only done 76000km. Their advice: s**** the car!! I asked if they checked the computer, the starter, the engine - no it can't be checked until the wiring is replaced. Are they telling the truth????