I have a FOI outstanding to them asking for various bits of info (which I doubt they collect, but want that in writing) which is now well overdue and my chaser to them has gone ignored.
You can take this to an internal review and then to the Scottish Information Commissioner if they still don't respond or if you're not happy with the response.
www.itspublicknowledge.info/YourRights/Askingforareview.aspx
There are time limits for doing this, so if it's more than 60 working days (12 weeks) since your original request you might have to start again.
You should ask for a review no later than 40 working days after the date you receive one of the above responses from the authority. If the authority did not respond at all, you have 40 working days after the end of the 20 working day period for responding to your request.