When you sign up and add your debit/credit card or when you add a new debit/credit card, a small pre-authorization charge is made on your credit or debit card for a specific amount, used to ensure your card is valid before you are able to make use of the service.
We do not capture this charge, instead it should be voided by your bank within 10 working days. However we unfortunately do not have control over the different issuing banks and their timeframes.