Alert Notifications on iPhone

Can someone tell me why SimpliSafe mobile app doesn’t let you set a custom notification alert? After several very unsympathetic calls to Customer Service it turns out it’s a known issue!! The cheapest of apps let you set an alert tone, and the tech department at SimpliSafe can’t come up with a fix? 
After switching away from my RING system, hundreds of dollars later I couldn’t be more disappointed, and will never recommend SimpliSafe to anyone I know.! I never know whether I’m getting an email, or if someone is on my porch…beyond frustrating!