iMessage and FaceTime not working with phone number.

Hi guys,

I've had this issue for days. My iMessage had been linked with my email. So I sign out of "my Apple ID" to enable me select my phone number as my preferred option for use. Unfortunately, I have my former phone number (which does not exist anymore) in grey and not my present phone number. So I'm stuck with my old contact and my email address for iMessage and FaceTime. I have tried toggling iMessage off and on, it keeps me on "waiting for activation" mode, deducts some airtime for SMS charge but still goes back to "iMessage unsuccessful".

Guys what can I do to link my active phone number to my iMessage and FaceTime.