Vacation Entitlement based on full years of service and odd vacation year

Thanks for the response ben_hensel but I guess I'm not sure what I'm doing. I tried fiddling with your formula to make it work in my sheet but got a return of 2 instead of 20.
I'm not super awesome at excel development and I appreciate the help. I can plug in a network table around here so i guess this is my job now.

See what you think of the attached.