To rectify errors in Clock/ Alarm app – Android

My application has been developed with some bugs The app is to set alarms with option to set alarms for Once, Daily or
for Custom dates.
The issue I am facing is that, When I am setting daily alarms,
the app rings for a few days (2-5 days) but then stops
working. In some devices the alarm is also not ringing in full screen when it is locked. But in some phones, it is ringing in
full screen.
The above errors are device and Android version specific.
The developer will have to check the source code and rectify the above issues, if the testing is successful in all devices
and versions.
Looking for Someone who has developed the alarm app
previously which is working fine.
If you have not developed any alarm app before, you would need to ensure and research before initiating the project. After satisfactory discussion, we can initiate.