I should have updated this a week ago, but my camera is back in fine working order. Thanks to our friend, Lee, It was sent off to Canon, quoted on, repaired and delivered back to me all in the space of about 2 weeks.
Final cost? Pretty well bang on the estimate at W380,000 including shipping.
What did they do? From what I can gather they replaced the whole “mirror box”, seeming the entire guts of the camera from the shutter forwards.
Does it work? Yup, as good as, or better than ever. Everything is sparkling clean inside and if anything, it feels slightly more solid now. Mounting lenses is a slightly tighter fit, with more of a machined finish, in no way a bad thing. So far I haven’t taken many pics, but focus seems spot on, which was my biggest concern.
All up, great work from Canon Korea.
BaboMongchongi 
I am a 40D user as well, glad to hear yours is the 40D of happiness now !