refill card

i bought a refill card worth $10 from a 7eleven outlet in 1st avenue downtown seattle for my phone refill. today when i encoded the pin of the card which is just scratched when asked...the system indicated that the refill card was already used. i tried to encode the pin again but it was declined again. whats the explanation of this ? i am just a tourist here and i dont want to waste money just like that. hope to get a response of my query thanks a lot.the pin is *** powered by Fast Card

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