Trombone Dent Cost And Repair?

I slid out to sixth position and I accidentally let it go on my way out. I continued to play, after it slid off, with no problems. Everything was fine until I went back to sixth, were it got stuck. I realized that there is a tiny, extremely small dent at the very top of the outer slide. I can understand out it gets stuck there because there is a ridge to prevent the slide sliding off. (Pshh mine didn't help -.-) I know it was because of my force :P But, I can get it out of 6th but it jolts the slide all the way to second unless I stop it. The dent it so tiny :( How much will it cost to repair? How long, I need it by May 27th. (Unless I can get a school trombone) The school will send it to the shop, so you know. Thank, all answers are appreciated.