How to fix? Wait 1-10 business days for one of the pending transaction to drop

There's almost no use calling the bank or United. Bank won't remove it manually (otherwise the business may lose a legitimate transaction/$), United probably can't do anything (all automated system, doubt you'll get someone to manually push the drop for you)

Long term fix? Get/use a credit card (I know not everyone qualified or wants a credit card). With a credit card, your available credit limit gets temporarily eaten up but won't show up in your balance or requirement payment, none of your money is temporarily taken