I recently had to warranty return my Surface Pro 3 power supply because only six months in it has split near the Magsafe-like connector. Getting a new one was easy, they asked a few questions, asked me to send them some digital photos of the old one, and then sent me the new one.
The CS said they didn't need the old one back. So I was going to throw it out as the old one looked "dangerous" to me (the split had wire coming out, etc). However the day the new one arrived I got an email from Microsoft with a pre-paid FedEx label in it asking for the old one back.
Now I might have been irritated by this but here is the exact text of the email (names removed):
> Hi ,
> You recently contacted Surface Support regarding an issue with your Surface that required a replacement power supply to be sent to you. So that we can better understand the nature of the issue with your power supply, we would like to collect the non-working power supply from you, if you still have the device. We understand if you do not, as we normally advise disposal of the non-working device.
> Attached to this email is a FedEx shipping label. Please print the shipping label provided, pack your non-working power supply into the same box your replacement arrives in, affix the shipping label, then drop off at a nearest FedEx location.
> If you have any questions or concerns, please call us at 1-800-Microsoft (1-800-642-7676). Thanks for your cooperation.
> Sincerely,
>
While they were inconsistent, the way the email was worded acknowledging the inconsistency definitely makes it better, and it also doesn't come across as demanding just a "if you can, that would be great, otherwise don't worry." I actually sent them the old PSU simply because the email was so polite and acknowledged their contradictory advice (and also I obviously hadn't thrown it out yet).
I am just posting this since it is effectively the same exact problem you had with Lenovo but handled in a massively better way.