They want you to waste time emailing them because it makes them look like they're doing it correctly and can spam you with a email survey.
As far as the answer to why the patcher gets stuck downloading..... well it could be a number of things....
A. Slow internet or ISP blocking
B. Bad Anti-virus/Firewall
C. Corrupted files or broken LocalConfig.xml
D. Strange UI not fully uninstalled.
Things to test... what is internet speed.... can you ping the game server.... do you have another game folder or TL client to check......