My neck's a bit saggy too, so have asked the OH for Slendertone's facelift in a box! Not sure quite how it works yet cos I won't open it until Xmas day, but my beautician was raving about it! My age doesn't help though cos I'm 50....
I would suggest lots of moisturiser and maybe twists using a broom handle for your waist, just sit on a straight-backed chair, put the broom handle behind your neck, hold on to both ends and swivel keeping your bum firmly on the seat.
Hope this helps? Incidentally my waist it 28 inches.....