Buy now, pay later (BNPL) apps have quickly risen in popularity – accounting for $142 billion in e-commerce transactions last year, according to a report from Worldpay. But some customers have reported that it can be difficult to get a refund if something goes wrong with the purchase, according to Charla Rios, deputy director of research at the Center for Responsible Lending, a nonprofit organization that educates the public about financial products.