SMS

Hi,
Is anyone having any issues with SMS not switching from iMessaging to text messaging when cellular or Wi-Fy is not available? I am running iOS9.2.1, and have had this issue since the beginning of iOS9. I have contacted Apple Care, and followed their instructions. They have advised me to turn iMessaging off when I am not connected to Wi-Fy or cellular data. I have the iPhone6. When I force to send as text message, I still get an error message that the message could not be sent, although the person I have sent the message to has received my text message. Mind you, that this is when I do not turn iMessaging off. It is just agrivating!