Can't unsubscribe from irritating MoMo SMS messages

Been trying for a month now to unsubscribe from irritating daily SMS messages to do with MoMo product. I've unsubscribed from all marketing messages on the MTN app, tried calling the call centre multiple times but there is no option to speak to an agent anymore and sent multiple messages top the customer care email address. Had 2 responses from them and both responses are not valid options when I tried to follow them. Can I suggest before advise is given, the customer care agents first test the advise thay are giving out to see if it's valid on their automated system. Also why is there no opt-out to these SPAM messages, is that not something that is a requirement nowdays? Really frustrating trying to deal with customer service and just want the irritating and unsolicitated SMS messages to stop please.