Skyrim’s DLC are language and region specific. Make sure you purchase the appropriate DLC that is compatible with your Skyrim version. Do not purchase the English language version if you want to play the DLC in any other language. You can check the BLUS/BLES code by looking on your disk or case.

BLUS-30778 for North America (English, French, Spanish)
BLES-01329 for UK/International (English only)
BLES-01330 for International (French, Italian, German, Spanish)

To be clear, the DLC are language specific. If you want to play DLC in German, make sure you purchase the German language version of the DLC.

Any customer service issues related to the Playstation Store should be directed to their support team.
https://support.us.playstation.com/app/contact_options/
http://uk.playstation.com/ps3/support/
http://fr.playstation.com/ps3/support/
http://de.playstation.com/ps3/support/
http://it.playstation.com/ps3/support/
http://es.playstation.com/ps3/support/