repeated messaging

I have been getting a message about congratulations and winning samsungs6. <br> There is no way for me to select that i do not want to participate in the survey and then they stop sending me the message.<br> I feel harassed.<br> Only way is to click on message then it takes me to website where i must take the survey. Where is the not interested option??<br> The message alert pops up almost every orher hour!