We often hear complaints that even though you have requested NOT have towels and sheets changed, it happens anyway. You are not alone, I have the same experience when I travel. Hotels will tell you this is a continuous training issue for their housekeeping staff. So when I travel, the first time it happens I usually ask/remind the housekeeping staff and front desk to please comply with my wishes.
Nevertheless, a well-meaning housekeeper may decide they need to be changed anyway (really, I am not that dirty—especially because I keep getting fresh soap every time I leave the room). So, I go to Plan B and simply leave the “Do Not Disturb” sign on my door for the rest of my stay. This plan works pretty well. Although, sooner or later security will show up at my door to make sure I am OK. It is actually pretty comforting to know they are checking on me and gives me another chance to let the hotel know I am just trying to save the planet, one towel at a time!