if you are a renter, you probably just got put on a list where owners that see this post won't rent to you anymore.
free upgrades for
DVC virtually never happen (except for maintenance issues as stated). for a renter to ask for an upgrade risks causing big headaches for an owner. (an owner asking for an upgrade just annoys all the other owners who wonder what makes this guy think he's that special...)
timeshares are different than hotels. completely different.