O.DOGG
Member
You're the umpteenth person to find themselves in this situation. Valve needs to add a second checkbox to the confirmation form informing users that they've opted to use a new payment method and so approving the transaction will temporarily lock them out of the market, and said period should literally be a few days, not a full week.
Well, you're lucky it only takes a week. I disabled SteamGuard the other day because Steam wouldn't accept the codes it was sending me to authorize one of my browsers and I can't trade for two weeks! Some bullshit that is.