NEED HELP

ok so i went black friday shopping. i had to wait in line for the TV i wanted i got the "one hour guarantee" card. well when i went to check out the cashier was like whats that?
i told her it was the card for the TV. well i showed her the ad. and she put 148 exactly on it.
well i guess she should of put tax on it as well because when i came home to officially register it it said insufficient funds.
ive called and called tring to get someone with no luck......
what can i do? i was supposed to have it bought by 1159. which i did....
but it doesnt need to be ordered until sunday.... i want to order it tonight tho...