Problem in Opel Vectra

If you have the tools and knowledge, do it yourself. If not, check the fuel pump in the tank. If diesel is reaching it, take it to an injection specialist; they'll fix it properly and ask for a free quote

Hi, if they've told you it's definitely a problem with the injection pump, I can't help you, but the same thing happened to me with my Vectra. Eventually, it would start, and no one knew what it was. It turned out to be the hoses going to the injection system; they're thin rubber hoses that were rotten, letting in air, which is why it wasn't working. I replaced them, and it's been fine ever since.