Relentless spam from MTN you cannot opt out of

I am a pre-paid customer of MTN. I cannot stop them from spamming me with their unsolilcited marketing. I have dia**** #135* as instructed on their spam sms's and every single consent has been withdrawn - i have painfully gone through every menu option, and there is no consent. I have installed the MTN app and ensured i have no consent. I have emailed MTN customer services and they just sent me instructions to dial 135 even though I specified i had already done this.

I am currently investigating legal remedies - beware, this company will not stop spamming you despite being asked to do so repeatedly.