On my S3mini there was a setting that when used, on receipt of a text which was not opened there and then a repeat tone used to sound every 5 mins or so to remind you that there was an unopened text..is that available on the A3 and if so how do you set it up?
Did a quick search and found this in Google Play store: Missed Call Reminder (link)
Let me know if that's what you're looking for.