I called and the CC people said they cannot "cancel" a pending charge, especially a legitimate one.

What I really find annoying is that Marriott let me go ahead with the transaction with a WRONG membership ID despite having my full name. I mean, why bother asking for my name IF you ain't gonna verify the name against the membership ID before allowing my transaction to go through?

I kinda assumed that if the membership ID doesn't match the full name, the transaction wouldn't go thru.