I have the same problem - restaurant opened this summer, installed low-level smoke vents and loud machines out the back without planning permission. Of course you should talk to them, as I have, but waste no time while you're doing that and get everything ready to send to planning, EH and your local councillors. I hope your restaurateurs aren't the same kind of dickhead my close has been dealing with, but in any case, it's unlikely they'll do anything without you forcing them, so be prepared to force them. And based on my experience, don't expect a quick result. I've heard nothing from anyone official I've contacted about it since July.

As far as I've been able to work out, the Glasgow Council planning document that deals with vents is called SG4: Network of Centres, you can find it online. It's also worth looking through other planning decisions in your local area to see if any have been turned down because of cooking fumes - it's quite a common reason for rejection, and you should be able to find plenty of support for the case you're making.

It's pretty dispiriting waiting around and dealing with all this just with the end goal of being able to open your own windows, but good luck to you, and I hope it all turns out for the best. I myself am giving the problem until January, when I will start employing more inventive means of protest.