iPhone 5 not receiving messages or calls

Out of the blue my iPhone 5 is no longer receiving messages or calls. I've checked with my provider and can confirm it is an issue isolated with my device.

People will attempt to call me and the caller's phone will ring normally before it diverts to voicemail. The messages app will not launch (white screen only) and if it does, all my messages are missing and if I try to send something it will stop 'sending' partway.

I've tried toggling the airplane mode, do not disturb function and tried a network reset without any success. My phone is on the latest software which is ios 8.4

I went the way and booked a Genius Bar appointment and was told it was because too many of my apps were crashing and the only thing they said they could do was offer to do a factory reset for my device which didn't solve the issue at all.

The only way I've found that worked is to hold down the home and sleep button to do a reset and magically I will receive calls and my messages will appear. Over time the issue will reappear and it means that I have to do a reset at least twice a day!

Has anybody had this issue? I am sick of having a phone that cannot make calls or texts :/ Any help would be appreciated