If you are cancelling within 14 days of buying a service online, you may be able to cancel without penalty. Read more about Right to Cancel.
If you are outside this time period, or it doesn’t apply, check the terms and conditions first to see if you can cancel and if there are any charges that apply. Then write to or email the business to inform them in that you wish to cancel the service.
First check your contract, is there a cancellation fee or a requirement to pay off the rest of your contract? This may be why you were charged. If this isn’t the case and you have been charged for a service that you are no longer signed up for, contact the business setting out your complaint. If the business does not respond or refuses to refund the money contact your bank or financial institution as soon as possible. You may be able to get the money back through a chargeback but you will need to act quickly! Read more about Chargebacks