Slightly off topic. I have recently tried booking a mini cruise to Amsterdam with DFDS. I initially went through the DDS website that showed a 30% discount. I also went direct to DFDS who offered an early booking discount of 20%. The result was that booking direct with DFDS was £25 cheaper than the DDS offer. I have had similar experiences with the DDS card in the past. However, I have also had some success especially with Samsung products and British Airways flights.