Hello @jtmott,
I sincerely apologize for the experience you've had thus far with the Go product, and I want to try and help. We've fixed a few notification alert problems that perhaps you have not pulled down in the app.
Before diving into the issues we've fixed, I wanted to say I'm unable to reproduce the problem you are having. If I use the Settings > Account > Your Notification Settings menu to disable notifications, I do indeed stop receiving them. Do you have a support case number I could go look over so we can perhaps get to the bottom of the problem together? In case you haven't updated the app in some time, there may be a few problems you are running into.
https://documentation.meraki.com/Go/Meraki_Go_-_Configuring_Notification_Settings
An issue existed on versions before 2.3.0 where it was not possible to change the alert settings, but this is no longer an issue.
There was a second problem where each device in the network would report a usage alert. This means that if a device was on the wireless network, you could potentially generate 3 usage alerts (one for the GR, GS, and GX). This was fixed in version 2.20.0 of the Meraki Go app and beyond.
