When you sign up to OVO we ask you to put in your credit card info. Like most e-commerce websites when you provide your credit card info we contact your bank straight away and ask them to 'preauthorise' your credit card. All that means is that your bank is checking that your credit card is legit and there's money in your account.
They do this by freezing $1 from your account - it's not actually taken out of your account, it’s just frozen by the bank and becomes available again in 1-9 working days.
If the $1 isn't released within 9 working days, let us know and we can follow up with your bank.