I found a way to stop the Xtratime pop-up at 1am every morning, uninstall all the updates to the MTN Menu WIG app that the sim installs, go to app info and one of the options there, under storage I think will remove all updates. That removes the Xtratime all together. Though that may depend on the age of your sim card, so another option would be to find a really old sim to do a sim swop on if you still get Xtratime after removing the updates.
The updates are what install Xtratime, after removing the MTN Menu updates all the old scam/spam options it installs don't work because they have obviously all been MTN server side deactivated because they are old campaigns.
You do till get other pop ups from the MTN menu app but not at 1am and not for xtraview...
You can also go to the app info and force stop the Mtn Menu app so that it can't spam you until you restart the device again, which on most devices can be days so not too much of a bother, so also a good option.