car manufacturers ripping us off.

I recently bought a Renault Laguna from a man who, in the past 2 years, had spent £6000 with a Renault dealer in an attemt to cure a fuel injection problem. It was cheap because it would not go. The dealer had now diagnosed that the car's computer needed replacing - for another £2000! Now I thought technology had been introduced to make finding a problem easy - just plug the car in & let the computer tell you what was at fault.
Of course, there is a charge for this simple service, in the case of my friend above, £45 each time. The "faulty" component was changed, the computer reset ( thus eliminating the fault), the car tested & returned to the customer, who pays his large bill & drives away happy. The problem then recurs two weeks later with the car bleating once again "fuel injection fault". The cycle is repeated with a different but equally expensive part replaced & the customer again relieved of a few hundred quid. No refund is offered for the unnecessary replacement of the last expensive but obviously faultless part. This goes on for about two years after which my friend gives up. I take the car to another dealer to be told the same thing - that the computer is faulty & needs to be changed. This also means changing the key card, the reader, the steering lock & the immobilizer as they are all programmed together. I bought a known good set from ebay & duly fitted it. The same problem still exists! Why cannot the diagnostics diagnose? If fuel is introduced into the inlet manifold the engine will start, so it is an injector fault - the computer is not telling them to operate although they are all in working order! A sensor is probably at fault but which one? If the car did not have any electronics it would be running perfectly!.
The rip off comes in many forms. Parts replacement, where new parts are fitted unnecessarily as the do not cure the problem. The customer is still charged. This is not good on an environmental level either as energy & resources were consumed to make this unneccessary part & a perfectly good part is thrown away! Because of this trial & error way of car repair is so expensive it means that cars which nay have plenty of real life left in them are scrapped. This enables the manufacturers to pass on an even more unnecessarily complicated vehicle to the motorist which he did not really want. The government will also pay you to trade in your 12 year old, 32000 mile mint Peugeot 106, when it will be scrapped despite having another 10 years service ahead of it!
30 years ago you could buy a Renault 4. Not the most comfortable or desirable of cars but a fine example of mechanical simplicity. If it did not go it was because the battery was flat, it had run out of fuel or the engine had siezed. A five minute poke around the engine soon found the problem.
I have a Volvo V70 which when I bought it did not have front fog lights, although all the wiring & connectors are there. I bought the lamps, the relay & the switch & plugged it all in. The did not work. I have to go to a Volvo dealer to have the computer reprogrammed to allow the lights to work! Why does the simle act of turning on fog lights have to go through a computer?
When is this stupidity going to stop?