Fix Klarna Payments on custom Woocommerce site

We have just installed and setup Klarna Payments UK which is the credit payment method on our uk based Woocommerce site, however it is not currently showing at the checkout. We have been in touch with Klarna support and they have said all is setup properly with them and also on our site, that the issue appears to be in the theme somewhere. Our theme is customised, so we need someone to diagnose the issue and fix it so that Klarna displays on the checkout page for customers to choose if they wish. Freelancer must have excellent knowledge of Woocommerce with customised theme experience and also setting up Klarna. Thank you in advance.