My phone is S-On (Locked). Yes, I do find this whole thing weird and I'm reluctant to send it to HTC because of the cost.
Is there no way I can just restore the operating system to how it was when I bought it? I know the factory restore doesn't work. Is the recovery option in the boot menu something different that might work?
Could I install a new operating system? This is probably at the extremes of my ability but with a full set of instructions I might work it out. And is it safe, not just for the phone but for any subsequent data I then put in - passwords etc.