Return Ferry ticket DOVER - DUNKIRK +

I have an open return ticket for the DFDS Ferry from Dover to Dunkirk for a car + passengers. The ticket can be used anytime until 13th December 2012. When you buy the ticket I will inform DFDS about the transfer by passing your details and send you the reference number that will allow you to travel. As an extra option the ticket also enables you to book yourself and your passengers into the VIP area for an additional 10,- per leg. Upgrading to first class is not mandatory though.