Truck radio

i have a 2008 silverado with am fm stereo with mp3 compatible cd player. the manual says it has seek scan digital clock auto tone control automatic volume auxiliary mp3input jack theftlock radio data system and xm radio.the problem is that i was going through the menu and seen auto vol.and i asumed that ,thats where the radio get louder or softer depending on how fast your driving well it did not work so i took the truck to the dealer and he set it the same way i did and said if that didnt fix it to bring it back anyway i did now they are saying the truck isnt equiped with that feature why would it be on the menu if it doesnt have it???????????????????????????????????????????//