It ain't supposed to slip, period! Anybody who says its "normal" don't know chit from Shinola. Could be a worn crank drive pulley letting the belt bottom out on the pulley. Or not enough tension on the drive belt, but all the tension in the world won't overcome a worn pulley. So the dealer is pretty much doin the ol'
" if ya cant convince em...confuse em " routine.
" But let me tell you something ,folks: You can't fix stupid! There's not a pill you can take, there's not a class you can go to. Stupid is forever!"