Your mistake was agreeing to anything before you had discussed both sides of the bargain. Before giving up your seat, you should know which flights you're being rebooked on (ideally the agent grabs that space so it doesn't disappear while they're processing the flight), when you're departing/arriving, what class of service you'll be in, and how much you'll be receiving. If you haven't discussed those details, you're not really ready to give up your seat. VDB is based on what the parties agree to. There is no $100 limit for arriving within two hours.