No disrespect mate but think about it, 2 starters and still the same problem. Your mate checked them both and they were ok.
Now in all the workshops I have worked and even when I was running my own. If a customer came in and wanted his car to start, I would sell him a starter and at the same time fit a relay even though all he needed was a relay. Why make $10 when you can make $40?
You yourself even pointed out the switch stuffs up. Oh well.