Jan 18, 2017 - 5:02 PM
in reply to Lucas
I did so and wow! They replied within few minutes! I quote the company's reply in case someone else has the same question as I did:
Thank you for your email and for being interested in our service.
Don't worry, you have time the whole day to return the device.
If you like to drop it at the pickup counter, the opening hours are daily from 06.00 to 23.30.
Otherwise you find Swiss post mailboxes in both departure halls.
Please let me know if you have any further questions.
Thanks once again Lucas!