Payment for Pay in 3 will automatically be collected from the debit or credit card you entered at checkout. The first payment is taken when the order is confirmed. The second and third are collected 30 and 60 days after the first instalment.
Klarna will notify you via email and push notification when a payment is due and when this has successfully been collected, or in the unlikely event of your payment failing. If a payment has been collected but you have not received payment confirmation, you can check the status of your order and payments by logging in at www.klarna.com/uk.