I used to valet with Leavinu and ARFNSX, but have since hung up my valeting shoes.
To, the OP: from everything I know about the valet agreement that you accepted when you took the ticket from the valet, you're basically screwed. Sorry. Most valet agreements say damage has to be reported before the vehicle is driven off the lot. If not, people could curb thier own sh*t and try to get the valet for a new set of wheels. You could try contacting the owner of the company, but it sounds like its been a good amount of time since it happened, so I'm guessing your screwed. Again, sorry.
As far as self parking, the valet usually won't care, as long as you give him some $. I mean, its a win win. The valet gets $, but doesn't have to do work for it. Just be very careful, cuz if you hit another customers car, you just entered the cluster f**k zone. And don't be an @$$ and park across 2 spaces or something like that.