How can I stop mtn mod unsolicited SMS alerts which is causing serious mental stress on me?

Sorry for the stress the MOD SMS issue has caused you. You can activate Do Not Disturb (DND) service on your line. The DND service can be activated by sending HELP to 2442 for free and is available in two modes:
• Fully Blocked Mode – Allows you to opt out totally from receiving promotional messages via SMS and IVR. This can be activated directly by sending STOP to 2442.
• Partially Blocked Mode – Allows you to filter specific service categories of promotional messages to be received. This mode will block ONLY THE CATEGORIES you selected and can be activated by sending the specific number of the option(s) to 2442