your carrier may charge for sms messages used to activate FaceTime

Hi,

In almost every 48 hours, I get the FaceTime notification message as you can see the attached photo. This message appears to me even though I am deactivating iMessage.

The issue is that my carrier in Saudi Arabia will automatically charge me once I click "OK" even though I am turning off the iMessage feature.

Is there anyway to stop this annoying message from coming out to my screen. Couple of times I pressed "OK" accidentally and charges hit my bill.

Any suggestions?

Thanks.