You will have seen its baby pink logo, placed seductively at the bottom of the checkout window. Today it’s ubiquitous, lurking on practically every online shop, from Amazon and Asos to Deliveroo and John Lewis. I avoided clicking it for a while, then eventually gave in: this is Klarna, one of the many buy now, pay later (BNPL) services that allow you to split payments for everyday items into three, zero-interest instalments, or pay within 30 days. Sounds like a perfect way to create some financial flexibility, right? That’s until you get completely hooked.