2FAC

I have a challenge on my Iphone 6. I used to receive 2FAC on my Zimbabwean number. Suddenly I am no longer receiving these codes when I tried to log on my Apple account while the login page tells me "a code has been sent to a number ending with ....". I then requested for Account recovery. I put my wife's number who is in Qatar for the process. I managed to do the recovery today. I then noticed the challenge still persist as I tried to add back my cell number as one of the Trusted contacts. I also tried to put my brother's Zimbabwean number and its not receiving any code. Only my wife's is receiving. Could Zimbabwean contacts barred from receiving 2FAC?

The other challenge is I can not find where I can turn OFF this facility on my Security settings. I logged in my account, tapped Account Security, under this I cant see where I turn Off the facility.