Ciao Fuechsl73
I have had to do this several times in the shop and am therefore familiar with this topic.
You can enter the SN of the hard disk here:
https://support.wdc.com/warranty...
There you can check if you still have warranty from WD.
In the business case, we send the disc back to the distributor, as WD does not handle support cases in Switzerland. I'm not quite sure how this works privately. You can possibly ask Digitec directly and otherwise you can certainly also send the disc to WD Germany - it simply takes 1 - 2 weeks.
Good luck!