We've been late for 16 minutes and have been charged 30 EUR regardless we've notified that we are in a traffic jam and could not get by car close to the apartment as this zone is prohibited to drive in. We had to run fast with suitcases and were late just a quarter an hour, but the rules are that strict. We had a phone call with the host, first he sounded kind and polite, later the discussion turned to be not that friendly. As a result, spoiled impression from the first day in Rome.
We've been informed that we are going to be charged if we are late for a minute after we have prepaid the apartment.