I made a call from the Renaissance MCO about 18 months ago to my parents in Chicago. I had bought the Wired for Business package (no free Boingo roaming at this property), and I decided to use the phone (since I had paid for it already). At checkout, I see a charge for about $5.63 for a 3-5 minute call. I told the front desk that I had purchased the WFB package, and they took the charge off after verifying that my call occurred before noon (since the package runs from noon to noon and I showed up after 12:30 pm with a late checkout).

20 euros for a 4 minute call is fairly expensive (although it sounds about right for a hotel), but at least the OP called a distant country. I realize that the marginal costs for a call 5-8,000 miles away isn't that much more than a call 700 miles away, but long distance companies charge based on where you call, not how much it costs them.