The 50 cents is not a charge. To initially verify your card, our PCI compliant service payment provider processes a hold for an amount of 50 cents, and immediately releases the hold. Some credit card issuers do not clearly denote this as a temporary hold - but you will see the transaction disappear in a 1-7 days. Again, it is not an actual charge and your card will only be charged on completing a ride.
If the hold doesn't disappear, you can send us an email at email@example.com, and we'll get to the bottom of it.