First, I have no experience with MarketStat or Gigspot. That said, I can tell you what I would do in the same situation for virtually any MSC.
If I felt the shop would not be removed, I would leave it as is until hearing back from the scheduler.
If there was a possibility it would be removed, and lose all my work, I would change the date to match the system in order to force it through. I would include a note in the report if possible and email every address I had explaining why.
Equal rights for others does not mean fewer rights for you. It's not pie.
"I prefer someone who burns the flag and then wraps themselves up in the Constitution over someone who burns the Constitution and then wraps themselves up in the flag." -Molly Ivins
Never try to teach a pig to sing. It's a waste of your time and it really annoys the pig.