A few years ago local mobile operators decided to create (and heavily market) prepaid plans that charged you a per week flat fee (if you had balance on your acc

A few years ago local mobile operators decided to create (and heavily market) prepaid plans that charged you a per week flat fee (if you had balance on your account). Turns out that (for most people) prepaid 3.50€/week mentally equates to 14€/month postpaid, whereas in reality it's closer to 15.20€/month (or an additional 8.7%, plus credit risk).