To reduce the ink coverage, as I said previously, you must either edit the image itself, or you must export to CMYK using an output profile with a lower ink limit. That said, until I know the color mode of that image (which I should see in the info panel), I don't know exactly what to suggest. The settings you used to export do not change the colors at all.
Frankly, I think the printer is a big source of the problem here, since they don't seem to have given you a set of specifications or a recommended profile. I understand, though, that you don't have a choice about working with them. 300% ink is really not unusual in offset printing, at least not with printers I use.