Good Morning Paul,
A reset could help and if your in warranty the phone manufacturer could help too.
Remove your sim card and wipe it down to remove any static build up.
Ensure no dust or lint is in the ports is the first thing to do.
Power down your phone and remove the battery for a while is another.
Here is a YouTube Clip showing how to perform a reset.
Ensure you carry out a back-up of your data first.
This is the link for Uk Samsung Mobile Repair servive.
http://www.samsung.com/uk/#mobile-devices-home
