Thanks Carl , yes I tried the one minute alarm to check it out. It wouldn’t work at first but then eventually it rang. It worked for a few days then Dad said it had stopped working so I tried it again. So far so good. It seems to be working at the moment. I just don’t understand why it’s intermittent. 

It seems to be working now but has not worked on several occasions before. The alarm feature wasn’t coming up at the set time so I don’t think it had anything to do with the volume. It’s my Dads phone so we will just see how it goes. I was just wondering if anyone else had had a problem with this. Many thanks for your reply Carl. 

While in the alarm clock app/screen, press volume button to increase alarm volume. Let me know if that's just the problem.