I'm not quite sure why the dealership just sold you the card on its own as it's a £200 coaster until you pay a main dealer to activate it via SVM to pull the codes from the server in Germany. The codes in the pack are only step 1 and not the activation codes that get pushed into the RMC unit.
There is no bypass around this like there is on the MMI 3GP and there will only be a handful of indies that have access to GeKO (AuDi server) so main dealer is pretty much your only option. I believe the labour charge is 100-150 on top of what you've paid already.
Normally the dealers will not have the Maps back as soon as you break the seal - same return policy as software normally has as once you have the step 1 code, you can activate strictly speaking. If they didn't tell you about the activation process you may get lucky.