Sorry you had a bad experience. I've never heard of a 20 minute match clock, not saying it couldn't have happened but I've only seen 30 minutes on any UPLUSA events or leagues.
If it really was a 20 minute match and they didn't adjust the handicap then you got royally screwed. The handicap is pretty tightly tied to the match length. It's not unheard of but milking the shot clock isn't as useful as you'd think. There are cases where it could matter but it's another thing that doesn't come up too often.