Prenzlberger Orange Bikes

I found a shop that rented bikes most cheaply in Berlin. The average rental price is around 12-15 € per day. Well I found a place that rented for 6 €, for 24 hours. The stall in question is manned by two German gentlemen who do not speak any English, but it is easy to understand them. I picked it up one day and decided to keep it the remaining 3 days. It is true, that the first day, after dark I was reluctant to leave the bike in the street, if anything happened. So at 6 I went to return it at closing time. The owner saw me coming and was surprised. I told him in English that I was reluctant to leave it in the street and, Mr., in perfect German, told me that there was no problem.