Transferring an RTM win10 pro key to a win10 home

[Tovino77]

Background information. I'm sick of the lack of controls, and customisability, that win10 home takes away from me. I also have an old XP machine, that somehow magically survived the win10 upgrade, and someone actually purchased an RTM key for it, at least when I checked the key, the app told me it was a win10 pro RTM key.

So here I am, wanting to transfer that RTM key given that machine is not being used on win10 anyway. So I went into CMD, sent it the command slmgr /upk, then tried enterring the key on the other machine. At that point, I got the typical error, which I was expecting, since I need to contact Microsoft to fully transfer. However, after going through the virtual agent, even after 2 hours, nothing happened at all. Keeps saying I'm in the cue, and that there's a (2 / 5) minutes waiting line. That, however, never changes. Where do I contact Microsoft, or how would I go about transferring this key over exactly? No, I've never done this before, and google appears to be a bit of a circle on this one.