Start here:
Contact Customer Care
Then select the applicable options for a CC app (like Photoshop or whatever CC app is part of the group you're trying to activate) then Licensing & Activation Help and you should get an option with a blue button that says Show me my contact options. Click that and it may give you a chat and a phone number. In the US it would, but I'm not sure about your country. This is the button in the US:

If you can type English (or if they have French chat help) I'd recommend Chat because you can copy-paste your redemption code into a chat window easier than reading it over the phone:

You might check here in case there is an automatic way to get around the issue:
Help with redemption codes