If a customer enters an incorrect postcode, they may be redirected to a 3D secure platform. Here they may be required to enter a password they have set up with their bank - Please read this article on 3D secure
As your security is of utmost importance to us, we work with our payment supplier, Stripe, to ensure you have as little fraudulent payments as possible. When authenticating a card or making a payment, the customer making the payment must match the postcode field perfectly.
Please see this article for more info on postcode validation here (you could send this to your customers if a payment is rejected). Ask the customer to check directly with the bank to see if the postcode they are trying to enter is the correct one registered with that card. If the customer is unable to contact their bank directly then please advise to use a different card.
This extra step of validation is an important way to help prevent fraudulent payments and therefore lead to less chargebacks to you.
If you have any questions about Collins Pay please email our Success Team on email@example.com