Loss of 3g service

Hello,

My IPhone 5S has recently started developing a problem after updating to iOS8.0.2 in that it keeps loosing data connections.

It hasn't done this before now? I have done a reset of the handset, as well as network settings and still no better.

The problem seems to go away for a short time after a reset using the home and lock button but comes back within an hour or so.

Is there any other way to solve this or will I have to take it to an Apple shop?

Thanks

Daniel