I sent my Linux laptop in for repairs to Dell. I needed the keyboard and trackpad replaced.
I wrote on the repair description, "Do not under any circumstances clear the hard drive or reinstall Windows" and "Beyond replacing the keyboard and touchpad, do not do anything to this computer" and "If you delete my hard drive or clear the password, I will demand a full refund and bill you for my time to reinstall the OS and data." And yet, I have my laptop back today with Windows 8.1 installed.
This is so infuriating I cannot tell you. What remedies are there for this when I was so crystal clear in writing and on the phone that I did not want this outcome?
When I send a machine for repair I have an old drive I stuff in it that has nothing on it except Windows. This way regardless of what they do my data never leaves my side and I won't lose anything. I'd suggest taking that approach if you ever have to do this again, because no "extra" instructions you give them will likely ever be followed. Honestly, you can't really blame them as they need a standard process that supports high volume, and custom instructions on every order would not make that reasonable.