[mothered]

So I tried everything and couldn't change anything.

That's because It was already In transit.

The only option (even when calling DHL) was to give it to an neighbor...

That would've been added to the special Instructions on the consignment, but the shipping address remained the same.

and I got the notification later that day that the package will be send back.

Given the package Is sitting In storage, you should now be able to provide a new address.