Klarna's latest acquisition comes at is looking to build out a stronger presence across Europe in payments. On the other hand, Wonga appears to be retreating from an attempt to pivot from lending to payments.
BillPay itself was founded back in 2009 as one of several e-commerce clones from Berlin-based incubating factory Rocket Internet, where BillPay was fashioned as the PayPal of Germany (Klarna, by the way, has also been described as the PayPal of Europe when pitching its business in the U.S.). Although many other Rocket clones eventually branched into other parts of Europe and the world, BillPay focused on dominating in one single, big country: Germany is known as the biggest e-commerce market in Europe. It is also operational in Switzerland, Austria and the Netherlands.
https://techcrunch.com/2017/02/06/klarna-buys-billpay-the-paypal-of-germany-for-75m-from-wonga/