Spam marketing company

I am forced to use MTN as they are the only provider of a reasonable signal where I live but I surely wish that I didn't have to. Having been an MTN user since July 2019 I make at least 5 requests a week to stop marketing **** messages and I keep receiving the "Thank you, you have been successfully removed from MTN's marketing list." *******. Is there not a law against spam marketing cr*p from these people. Reading through the reviews it would seem a having a decent network is enough to remove any obligation to provide customer service