MTN keeps spamming me via USSD push

For the last few weeks, I’ve been getting these random USSD push notifications welcoming me to MTN’s “CallerXchange” service these types of notifications cannot be turned off as it comes from the sim and they completely Hijack your screen and the phone cannot be used until you press ‘accept’ or ‘cancel’. This is happening up to four times a day. Some days worse than others. This is not a new contract and I have not changed anything recently. What the hell are you doing MTN?