I cannot delete texts from my iPhone 4s and now 5c without freezing and/or stop receiving/sending texts.

I had had my iPhone 4s for 2.5 years. If I would try to delete text threads it would completely freak out. I wouldn't be able to send or receive texts or calls until turning the phone off and back on again. After that, I would go back to the messages app and all the text threads I had previously deleted would be back. I recently got an iPhone 5c because the problem on my 4s got so out of hand; it is doing the exact same thing. I was just wondering if anyone has had this problem and has found a solution for it? I have not gone to the Apple Store about it yet but I will soon. All in all, very disappointing from a device that is supposed to be sophisticated. Calls/texts are what the phone is for after all; it's very irritating that it can't perform basic tasks like texting and deleting messages.