I get your feeling OP but unfortunately it is perfectly normal than GMs don't deal with those cases, because people do A LOT of mistakes when biding on a plot and GMs can't put that much of time dealing with these mistakes.
IRL, I work all day with people who do things on a rush and don't read ; most of my time is taken by fixing their mistakes for them, so maybe I'm a little biaised here, sorry.
Plus, withdrawing could cause many problems during biding times, with people trolling. This is why is not allowed.
I hope you'll manage to grab your M plot on the next turn.