Update: DHL returned today without warning but when I asked them if they had a label he looked in his van and found one and took my DTK.

Same here (UK) contacted Apple support who sent me to the same generic dtk return page and told me to contact DHL who have no clue what to do. Email was as below "Please note that you would nee to contact your local DHL to obtain additional information relating the pick up booking and the return label. If they are unable to assist you I would ask you click on this link to be directed to another support page relating this issue."