15 Day ban for opening from the start of the game as a 5 man.

I was playing as a 5 man queue in normal blind pick with some friends and we were joking around in champ select. We had locked in things we didn't actually want to play and thought one of us would dodge. No one ended up dodging because no one wanted the penalty, and we all had the wrong runes/masteries and most took tp/ghost. We did not want to play out the game so we all ran into the enemy base hoping they would end as fast as possible. We didn't want to wait for surrender, and thought this was the fastest way to get out of the game. The enemy team ended at 13:45, and 4 of us ended up getting banned. There was no intention by us to ruin the game, we just wanted to get out of the game because we had messed up in champ select. During the game we were competing to see who could make it to the enemy fountain most times, trying to make the best of the poor situation. None of us have ever been punished before, and we were honestly just trying to get out of the game. Any advice/thoughts? Thanks