said by en102:I've been there before... Pearson International - terminal 2, 2 years ago.
ME: I'm here to pick up my rental, here's my reservation
Rental Agent: We don't have any of those left, but I'll rent you $25/more a day car for only $15/more a day.
ME: Why should I pay more ?
Rental Agent: There are some other smaller vehicles, if you don't want to wait for another hour, or pay extra.
Of course, I sent a message to the corporate of this car rental agency for bait and switch. Typically, I've seen this with Enterprise and not Avis... but there's always an exception.
I had the same thing happen to me using enterprize in Seattle Wa. When I went to pick up my car they said that they didn't have it. They did upgrade me to the next level with no additional cost so it worked out ok for me.