Vauxhall Combo won't start

My van firstly wouldn't start, I took it in the garage as it had an engine management light on. I had a recon starter motor and my van worked again. But the engine management light was stil on, I took it to be diagnosed and the fault code po0126 (I think) came up, which is injector faults. My van then had trouble starting in the mornings. I would need to keep turning over for 5 mins before it would start. Once started it was ok until left overnight. This went on for 2 weeks, then my starter motor went again. I took the van to a diesel specialist and they told me I have an electrical fault. I feel like I'm being given the run around. Has anyone had a similar problem and actually know what is wrong? I would appreciate any advice. Thanks.