RoboKiller hosed my voicemail after uninstalling it and they didn't hose it via my device but actual voicemail line got hosed and AT&T has tried to fix it with

RoboKiller hosed my voicemail after uninstalling it and they didn't hose it via my device but actual voicemail line got hosed and AT&T has tried to fix it with no avail. Best solution I've found on iPhone --> Do NoT Disturb --> only allow calls from contacts. Receive texts notifications only from contacts too.