Having taken our credit card details, Europcar helped themselves to an extra days rental fee. They sent us an invoice claiming that we had collected the car whilst still flying over Belgium and returned the car more than a day late when we'd been home for nearly a day! Europcar are stonewalling and lying to our Credit Card company who don't seem to be trying too hard for us. Having scoured the internet it seems that kind of practice is widespread within Europcar. It is probably even in their business plan!
Do not use Europcar and if you use an intermediary insist that they do not use Europcar.