I am so mad! I just got charged double for something I only got one of! 
Oh my, I hope it was only a sincere error and not the charger being malicious
The check out person didn't look the brightest and I should have known to check before I left.  The place is like 30 minutes away.  Now it's not worth wasting the gas to get it fixed.
Ugh that must be so aggravating that you can't even get your money back. I would suggest calling and telling the manager.