The double charge that you see on your bank statement is most likely an authorisation (pending charge), rather than a real charge.

When making a payment with a credit card or with a debit card for certain services, your credit card company or bank may authorise your card before the actual funds are taken. If this is the case, the authorisation appears on your bank statement in addition to the real charge. The authorisation should disappear from your bank statement within a month.

We would also advise contacting your bank to see whether this is what has happened. 

If you need any further clarification, feel free to contact our support team.