Did you follow the video and remove the files from the folder specified? If you did and it still hasn't worked then I'm unsure really.. Could be down to a number of reasons i guess and it might be prudent to simply wait it out. As for trusting the operative from Microsoft I'd say she was trying to avoid you paying extra so it sounds pretty legit to me..
I've called Microsoft again and this time the fellow confirmed it is because of two reasons -
1) the high volume of downloads
2) there is a known problem with this MediaCreationTool.
He said they're working to fix it and it could be up to 24 to 48 hours before everything should be back to normal.
Remembering the first gal I talked to today from Microsoft said to keep trying it every five minutes or so - the last chap I talked with gave me what I just posted to you. A year from now, all should be solved!