They just caused more problems

Our Corsa Lite had a slow starting problem, but once it was running it was fine. We took it to Menlyn Motor Services to have the fuel injectors tested. They found no problem with the injectors and asked to keep the car longer to do other tests. They had the car for 3 days. They couldn't found the starting problem but now the engine cuts out when car is cold. After a while the idling became better but if you switch on the aircon it became irregular and creates lot of vibration in car. We took it back, but they couldn't find the cause of the idling problem and now blames the computer box. We had no problems with the idling before we took it to them. Also after the second visit a thick red cable hangs out underneath the dashboard on the driver's side. They claimed it was there, but there is no way one would have overlooked it when getting into the car.