We got used to the system where a person comes up to you with this fancy handheld devic. You hand over some cash and you may then park for a certain period.
On Wedensday I parked in town and payed for an hour. We got back to the car in exactly 60 minutes. The attendant approached me and asked for some more money.
Some words were exchanged before I realised that she took the money for one hour but only entered the amount for 30 minutes onto the system.
I did not ask for a receipt. :( Thus my word against hers. Hand over more money, OR ...
LESSON: Get a receipt when you hand money over to these attendants !!!
Alternatively convice your collegues to go to meetings on the back of your bike. :)